:
1 After these things the word of the LORD came unto Abram in a vision, saying, Fear not, Abram: I am thy shield, and thy exceeding great reward. 2 And Abram said, Lord GOD, what wilt thou give me, seeing I go childless, and the steward of my house is this Eliezer of Damascus? 3 And Abram said, Behold, to me thou hast given no seed: and, lo, one born in my house is mine heir. 4 And, behold, the word of the LORD came unto him, saying, This shall not be thine heir; but he that shall come forth out of thine own bowels shall be thine heir. 5 And he brought him forth abroad, and said, Look now toward heaven, and tell the stars, if thou be able to number them: and he said unto him, So shall thy seed be. 6 And he believed in the LORD; and he counted it to him for righteousness. 7 And he said unto him, I am the LORD that brought thee out of Ur of the Chaldees, to give thee this land to inherit it. 8 And he said, Lord GOD, whereby shall I know that I shall inherit it? 9 And he said unto him, Take me an heifer of three years old, and a she goat of three years old, and a ram of three years old, and a turtledove, and a young pigeon. 10 And he took unto him all these, and divided them in the midst, and laid each piece one against another: but the birds divided he not. 11 And when the fowls came down upon the carcases, Abram drove them away. 12 And when the sun was going down, a deep sleep fell upon Abram; and, lo, an horror of great darkness fell upon him. 13 And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years; 14 And also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance. 15 And thou shalt go to thy fathers in peace; thou shalt be buried in a good old age. 16 But in the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full. 17 And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces. 18 In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates: 19 The Kenites, and the Kenizzites, and the Kadmonites, 20 And the Hittites, and the Perizzites, and the Rephaims, 21 And the Amorites, and the Canaanites, and the Girgashites, and the Jebusites.
Previous Chapter
Next Chapter
[AD 397] Ambrose of Milan on Genesis 15:1
Because Abraham did not seek recompense from man, he received it from God, as we read in Scripture: “After these words the Lord spoke to Abraham in a vision saying, Fear not, Abraham, I will protect you. Your reward will be exceedingly great.” The Lord is not slow to reward. He is eager to promise, and he gives in abundance, lest any delay cause weak souls to repent of having despised visible things. He pays back, so to speak, at high interest, rewarding with great abundance the one who has not been seduced by the things of this world that were offered to him.

Source: ON ABRAHAM 1.3.18
[AD 407] John Chrysostom on Genesis 15:1
God said to him, “Don’t be afraid, Abram.” Notice the extraordinary degree of his care. Why did he say, “Don’t be afraid”? Since Abraham had scorned so much wealth by giving little importance to the offerings of the king, God said to him, Have no fear for despising gifts of such value. Do not be distressed on the score of your diminished prosperity. “Don’t be afraid.” Then to cheer his spirit further, he adds his name to the encouragement by saying, “Don’t be afraid, Abram.” It proves to be no little help in encouraging a person to invoke the name of the person we are addressing. Then he said, “I am your shield.” This phrase is also rich in meaning: I summoned you from the Chaldeans. I led you to this point. I rescued you from the perils of Egypt. I promised once and again to give this land to your descendants. It is I who will be your shield. After daily making you acclaimed by all, I will be your shield—that is, I will struggle in your place. I will be your shield. “Your reward will be exceedingly great.” You refused to accept reward for the troubles you suffered in exposing yourself to such risks. You scorned the king and what he offered you. I will provide you with a reward, not to the degree that you would have received but wonderfully, exceedingly great. “Your reward,” the text says, remember, “will be exceedingly great.”

Source: HOMILIES ON GENESIS 36.10
[AD 735] Bede on Genesis 15:1
After these things, the word of the Lord came to Abram in a vision, saying, "Do not fear, Abram, I am your shield; your reward shall be very great." The blessing that Abraham had received from the priest Melchizedek, the Lord himself now confirms. For the priest had said, "And blessed be God Most High, who has delivered your enemies into your hand" (Gen. 14:20). The Lord says, "I am your shield." The priest had said, "Blessed be God Most High." God himself says, "And your reward shall be very great." By reward he means not only the affection he had shown to his brother in distress but also all the devotion with which he had served the Lord with a whole heart since he left his homeland and relatives.

Source: Commentary on Genesis
[AD 397] Ambrose of Milan on Genesis 15:2-3
Let us also consider what recompense he requests from the Lord. He does not ask for riches, as would a greedy person, nor for a long life in this world, as would one who fears death, nor for power. Rather he asks for an heir worthy of his work. “What will you give me?”—he says—“I am about to depart without children.” And then he says, “Because you have not given me posterity, a slave born in my house will be my heir.” Let everyone learn therefore not to despise marriage. Let them not unite with disreputable persons, so as not to have children of such a standing that they are unable to be their heirs. In view of the inheritance to be transmitted, if they are not moved by any consideration of decency, they at least should desire a worthy marriage.

Source: ON ABRAHAM 1.3.19
[AD 397] Ambrose of Milan on Genesis 15:2-3
But the holy and prophetic mind is more concerned with an eternal posterity. What Abraham desires is in fact the offspring of wisdom and the inheritance of faith. This is why he says, “What will you give me, since I am about to depart without children?” What he desired was the progeny of the church. What he was requesting was a descendancy that would be not servile but free, not according to the flesh but according to grace.

Source: ON ABRAHAM 2.8.48
[AD 407] John Chrysostom on Genesis 15:2-3
Since God had promised him a reward, a wonderfully, exceedingly great reward, Abraham revealed his grief of spirit and the disappointment affecting him constantly on account of his childless condition. He says, “Lord, what sort of thing will you give me? After all, you can see, I have reached the height of old age and am to pass on without children.” See how from the outset the just man showed his sound thinking in calling his departure from here a “passing on.” I mean, people who live an assiduous life of virtue really pass on from struggle, as it were, and are freed from their bonds when they transfer from this life. You see, for people living virtuously it is a kind of transfer from a worse situation to a better, from a temporary existence to an everlasting one that is protected from death and has no end.

Source: HOMILIES ON GENESIS 36.11
[AD 407] John Chrysostom on Genesis 15:2-3
These words reveal the extreme degree of the pain in his soul. [It is if he were saying] to God, Far from being granted what my slave was, I am to pass away without child or heir, whereas my slave will inherit the gifts granted me by you, despite the promise received from you more than once in the words “to your descendants I will give this land.” Consider, I ask you, the just man’s virtue in this case also in the fact that while entertaining these thoughts in his mind he did not protest nor say any harsh words. Instead, driven on in this case by the words spoken to him, he spoke boldly to the Lord, revealed the tumult of his interior thoughts and made no secret of the wound to his spirit. Hence in turn he received instant healing.

Source: HOMILIES ON GENESIS 36.11
[AD 420] Jerome on Genesis 15:2-3
(Chapter 15, Verses 2, 3.) Lord God, what will you give me? And I go without children: and the son of my household, this Damascus Eliezer. And Abram said: Behold to me you have not given seed: and the son of my household will be my heir. Whereby we have, and the son of my household: in Hebrew it is written, Uben Mesech Bethi: which Aquila translated, the son of the one who gives drink to my house: that is, the son who gives drink to my house. But Theodotius, and the son of my servant: that is, his son, who is in charge of my house. And as for what he says, this is it: I die without children, and the son of my steward, or overseer, who manages and distributes all the food of my household, is called Damascus Eliezer, and he will be my heir. Moreover, Eliezer means 'my God is my helper'. They say that Damascus was founded and named after him.

Source: Hebrew Questions on Genesis
[AD 735] Bede on Genesis 15:2
And Abram said: Lord God, what will you give me? I go childless, and the son of the steward of my house is this Damascus Eliezer. And Abram added: You have given me no offspring; and behold, my servant will be my heir. He does not ask as though doubtful of God's promises, but simply inquires what reward he, who has no son in whom to rejoice as heir and participant of the divine promise, will receive from the Lord, and whether his servant will be his heir instead. This servant was called by two names, that is, Damascus, Eliezer, by whom, they say, the city of Damascus was both founded and named. But the Lord, favoring Abram's desires, promised him this reward which he sought, when he immediately added:

Source: Commentary on Genesis
[AD 397] Ambrose of Milan on Genesis 15:4
But if the words of Abraham are not enough to correct, consider the word of God, who condemns such a mode of transmitting inheritance. “This man shall not be your heir,” he says, “but the other who will come out from you, he will be your heir.” Who is this other of whom he speaks? In fact Hagar too bore a son, Ishmael, but he is not speaking of him. Instead, he is speaking of holy Isaac. For this reason he added “who will come out from you.” In fact, the one who truly came out of Abraham is the one who was born of a legitimate marriage. But in Isaac, the legitimate son, we can see the One who is the true legitimate son, the Lord Jesus, of whom at the beginning of the Gospel according to Matthew we read that he is the son of Abraham. He was the true heir of Abraham, bringing renown to the descendants of the progenitor. Through him Abraham looked up to heaven and understood that the splendor of his posterity would be no less luminous than the radiance of the stars of heaven. As “one star differs from another in brightness, so it is also for the resurrection of the dead,” said the apostle. The Lord, in joining to his resurrection people whom death was accustomed to hide in the ground, made them sharers in the heavenly kingdom.

Source: ON ABRAHAM 1.3.20
[AD 735] Bede on Genesis 15:4
This one shall not be your heir; but one who will come from your own body shall be your heir. This is proved by reason to have been said about Isaac and his offspring; of whom it was later heard: In Isaac shall your seed be called. For the sons of the concubines, although they were the seed of Abraham, could not be partakers of his inheritance; and since to this inheritance beloved by God, in which the divine protection and great reward would exist, only heavenly souls pertain, it is fittingly added:

Source: Commentary on Genesis
[AD 56] Romans on Genesis 15:5
For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith. For if they which are of the law be heirs, faith is made void, and the promise made of none effect: Because the law worketh wrath: for where no law is, there is no transgression. Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, (As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were. Who against hope believed in hope, that he might become the father of many nations; according to that which was spoken, So shall thy seed be. [Genesis 15:5] And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara's womb: He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; And being fully persuaded that, what he had promised, he was able also to perform. And therefore it was imputed to him for righteousness. Now it was not written for his sake alone, that it was imputed to him; But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead; Who was delivered for our offences, and was raised again for our justification.
[AD 99] Clement of Rome on Genesis 15:5-6
Abraham, styled "the friend," [Isaiah 41:8] was found faithful, inasmuch as he rendered obedience to the words of God. He, in the exercise of obedience, went out from his own country, and from his kindred, and from his father's house, in order that, by forsaking a small territory, and a weak family, and an insignificant house, he might inherit the promises of God. For God said to him, "Get you out from your country, and from your kindred, and from your father's house, into the land which I shall show you. And I will make you a great nation, and will bless you, and make your name great, and you shall be blessed. And I will bless them that bless you, and curse them that curse you; and in you shall all the families of the earth be blessed." [Genesis 12:1-3] And again, on his departing from Lot, God said to him, "Lift up your eyes, and look from the place where you now are, northward, and southward, and eastward, and westward; for all the land which you see, to you will I give it, and to your seed forever. And I will make your seed as the dust of the earth, [so that] if a man can number the dust of the earth, then shall your seed also be numbered." [Genesis 13:14-16] And again [the Scripture] says, "God brought forth Abram, and spoke unto him, Look up now to heaven, and count the stars if you are able to number them; so shall your seed be. And Abram believed God, and it was counted to him for righteousness." [Genesis 15:5-6] On account of his faith and hospitality, a son was given him in his old age; and in the exercise of obedience, he offered him as a sacrifice to God on one of the mountains which He showed him. [Genesis 22:9]

Source: Clement's First Letter to the Corinthians, Chapter 10
[AD 397] Ambrose of Milan on Genesis 15:5
What is the meaning then of the expression “he brought him outside”? The prophet is as it were led out, so that he goes outside of the body and sees the limitations imposed by the flesh that is his garment and the infusion of the Holy Spirit who makes a kind of visible descent. We too must exit from the confinement of this our temporary dwelling. We must purify the place where our soul dwells from all uncleanness, throw out every stain of wickedness, if we wish to receive the spirit of wisdom, because “wisdom will not enter a wicked soul.” Abraham believed, not because he was drawn by a promise of gold or silver but because he believed from the heart. “It was reckoned to him as righteousness.” A reward was bestowed that corresponded to the test of his merit.

Source: ON ABRAHAM 2.8.48
[AD 735] Bede on Genesis 15:5
He brought him outside and said to him, "Look toward heaven and number the stars, if you can," and he said to him, "So shall your offspring be." For the just and the elect are rightly compared to stars, not only because, like the stars, they cannot be counted by men; but also because they are exalted with heavenly happiness, because they transcend the base and low desires of this life with great sublimity of mind; because they shine among the reprobate as lights in the world, holding the word of life. Of such it may rightly be said in the end: "Star differs from star in glory, so is the resurrection of the dead" (1 Cor. 15:41). But what he said, "So shall your offspring be," he does not say only of those elect who were to be born corporally from his lineage but also of us, to whom it is said by the Apostle: "If you belong to Christ, then you are Abraham's seed" (Gal. 3:29). Hence, he first heard while being situated inside: "But one who will come from your body will be your heir." Obviously for those who were to emerge from his seed, who were also to become co-heirs of the promised blessing and inheritance. Afterwards, bringing him outside, he commands him to number the stars, if he can; saying, "So shall your seed be," undoubtedly because of those who were not to be procreated from his body, but were still to be gathered as his seed from the whole world; in accordance with what the Lord himself said in the Gospel to the believing centurion, who not carnally but spiritually pertained to the seed of Abraham: "I say to you that many will come from the east and west, and will sit with Abraham, Isaac, and Jacob in the kingdom of heaven" (Matt. 8:11). For he brought him outside so that he might learn that he was yet to receive the seed of blessing in the breadth of the whole world. He commands him to look toward heaven and number the stars, so that he might know that he was to be enriched with this inheritance in the heavenly homeland.

Source: Commentary on Genesis
[AD 49] James on Genesis 15:6
What doth it profit, my brethren, though a man say he hath faith, and have not works? can faith save him? If a brother or sister be naked, and destitute of daily food, And one of you say unto them, Depart in peace, be ye warmed and filled; notwithstanding ye give them not those things which are needful to the body; what doth it profit? Even so faith, if it hath not works, is dead, being alone. Yea, a man may say, Thou hast faith, and I have works: show me thy faith without thy works, and I will show thee my faith by my works. Thou believest that there is one God; thou doest well: the devils also believe, and tremble. But wilt thou know, O vain man, that faith without works is dead? Was not Abraham our father justified by works, when he had offered Isaac his son upon the altar? Seest thou how faith wrought with his works, and by works was faith made perfect? And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God. [Genesis 15:6] Ye see then how that by works a man is justified, and not by faith only. Likewise also was not Rahab the harlot justified by works, when she had received the messengers, and had sent them out another way? For as the body without the spirit is dead, so faith without works is dead also.
[AD 50] Galatians on Genesis 15:6
O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you? This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith? Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh? Have ye suffered so many things in vain? if it be yet in vain. He therefore that ministereth to you the Spirit, and worketh miracles among you, doeth he it by the works of the law, or by the hearing of faith? Even as Abraham believed God, and it was accounted to him for righteousness. [Genesis 15:6] Know ye therefore that they which are of faith, the same are the children of Abraham. And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed. So then they which be of faith are blessed with faithful Abraham. For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them. But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith. And the law is not of faith: but, The man that doeth them shall live in them. Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree: That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith.
[AD 56] Romans on Genesis 15:6
Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, (As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were. Who against hope believed in hope, that he might become the father of many nations; according to that which was spoken, So shall thy seed be. And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara's womb: He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; And being fully persuaded that, what he had promised, he was able also to perform. And therefore it was imputed to him for righteousness. [Genesis 15:6] Now it was not written for his sake alone, that it was imputed to him; But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead; Who was delivered for our offences, and was raised again for our justification.
[AD 397] Ambrose of Milan on Genesis 15:6
And how did Abraham’s progeny spread? Only through the inheritance he transmitted in virtue of faith. On this basis the faithful are assimilated to heaven, made comparable to the angels, equal to the stars. This is why he said, “So will your descendants be. And Abraham,” the text says, “believed in God.” What exactly did he believe? Prefiguratively he believed that Christ through the incarnation would become his heir. In order that you may know that this was what he believed, the Lord says, “Abraham saw my day and rejoiced.” For this reason “he reckoned it to him as righteousness,” because he did not seek the rational explanation but believed with great promptness of spirit.

Source: ON ABRAHAM 1.3.21
[AD 407] John Chrysostom on Genesis 15:6
Accordingly let us learn, I beseech you, a lesson for ourselves as well from the patriarch: Let us believe in the words of God and trust in his promise. Let us not apply the yardstick of our own reasoning but give evidence of deep gratitude. This, you see, will succeed in making us also be seen to be righteous and will quickly cause us to attain to the promise made by him. In Abraham’s case, however, the promise was made that a complete multitude would develop from his descendants. The effect of the promise was beyond the limits of nature and human logic. Hence faith in God won righteousness for him. In our case, … if we are alert enough to see it, he promised much more. We are able in great measure to transcend human reasoning, provided we believe in the power of the One who promises, in order that we may gain also righteousness from faith and attain to the good things promised.

Source: HOMILIES ON GENESIS 36.15
[AD 735] Bede on Genesis 15:6
He believed God, and it was reckoned to him as righteousness. The Apostle recalls this sentence (Rom. IV, 3) to commend the grace of God, lest circumcision should boast, and the uncircumcised nations should be unwilling to admit to the faith of Christ: for this was done when faith was reckoned to the believing Abraham for righteousness, and he had not yet been circumcised. Therefore, faith is reckoned as righteousness, not idle and naked, but that which works through love; and also, faith which, although it does not yet have the time to work, still has a perfect will to work. For the faith of the thief was reckoned as righteousness, which, even though it could have no time for works given the imminent article of death, was judged so perfect by the inspector of hearts, that on the same day, it was rewarded with habitation in paradise with him. The faith of Cornelius and his household was reckoned as righteousness, even so much that before the washing of regeneration, they received the gift of the Holy Spirit; because as soon as it was conceived in the heart, it was prepared to work through love. Thus, Abraham's faith was also proven sufficient to be reckoned as righteousness, since he was prepared to offer even his only son as a burnt offering at the command of the Lord. Therefore, the just man lives by faith (Rom. I, 17), that faith surely which is ready to work through love, and if it has time, it works.

Source: Commentary on Genesis
[AD 420] Jerome on Genesis 15:7
(Verse 7.) I am God, who brought you out from the land of the Chaldeans. This is what we said a little while ago is written in Hebrew: who brought you out from Ur of the Chaldeans, that is, from the fire of the Chaldeans.

Source: Hebrew Questions on Genesis
[AD 735] Bede on Genesis 15:7
And he said to him: I am the Lord, who brought you out of Ur of the Chaldeans, to give you this land to possess it. Some think Ur is the name of a place, but because Ur is interpreted as Fire, it is better understood according to the tradition of the Hebrews, as we said above, that he was rescued from the fire of the Chaldeans, who wanted to consume him with flames because he refused to worship and adore the fire which they worshipped as God. But, with God protecting him, they could not accomplish this.

Source: Commentary on Genesis
[AD 735] Bede on Genesis 15:8
But he said: Lord God, how am I to know that I shall possess it? Abraham is not to be thought to have failed in faith after he believed in God, and it was counted to him as righteousness, so as to say: Lord God, how am I to know that I shall possess it? For he is not seeking a sign to believe as if he were still unbelieving; rather, he entreats that some similarity be given to the thing he believed would happen, by which the manner of it being achieved might be recognized. Hence the old translation has more significantly: Sovereign Lord, according to what shall I know that I will be its heir? Just as there was no lack of faith in the Virgin Mary when she said: How will this be, since I do not know a man (Luke 1:34)? She was certain of what was to come, she inquired about the manner of how it would happen. And when she had asked this, she received an answer. Consequently, here too a similitude was given from the animals: a heifer, a goat, a ram, and two birds, a turtledove and a pigeon, so that he might know through these that what was to come would surely come.

Source: Commentary on Genesis
[AD 430] Augustine of Hippo on Genesis 15:9
Here also, in fine, a symbol was given, consisting of these animals: a heifer, a she-goat, a ram and two birds, a turtledove and pigeon, that he might know that the things which he had not doubted should come to pass were to happen in accordance with this symbol. The heifer may be a sign that the people should be put under the law, the she-goat that the same people were to become sinful, the ram that they should reign. Perhaps these animals are said to be of three years old for this reason: that there are three remarkable divisions of time, from Adam to Noah, and from him to Abraham, and from him to David. David, on the rejection of Saul, was first established by the will of the Lord in the kingdom of the Israelite nation. In this third division, which extends from Abraham to David, people grew up as if passing through the third age of life. Or perhaps it may be that they had some other more suitable meaning. Still I have no doubt whatever that spiritual things were prefigured by them as well as by the turtledove and pigeon.

Source: City of God 16.24
[AD 542] Caesarius of Arles on Genesis 15:9
Therefore the heifer, the she-goat and the ram of three years, as also the turtledove and the pigeon, presented a type of all nations. They were described as of three years, because all the nations were to believe in the mystery of the Trinity. Now the entire Catholic church has not only spiritual members but carnal ones also, for although some say they believe in the Trinity, they are nevertheless carnal because they neglect to avoid sins and vices. Since there are spiritual souls with the carnal ones, for this reason the turtledove and pigeon were added. In the latter, spiritual people can be meant, but in those other three animals carnal people are understood.

Source: SERMON 82.1
[AD 735] Bede on Genesis 15:9-10
The Lord replied: "Take for me a three-year-old heifer, a three-year-old goat, and a three-year-old ram, also a turtledove and a pigeon." He took all these and divided them in half, and placed each half opposite the other, but he did not divide the birds. For the heifer may signify the people under the yoke of the law; the goat the same people who would be sinful, the ram the same people who would also reign. Therefore, these animals are called three because in the third age of the world that people matured and entered the land of promise. The first age is from Adam to Noah, the second from Noah to Abraham himself, the third from Abraham to David; in which the people were saved from Egyptian servitude and transferred to the land of promise. Or if these signify something else more fitting, I would by no means doubt that the spiritual are prefigured in the addition of the turtledove and the pigeon; and thus it is said: "But he did not divide the birds," because the carnal are divided among themselves, but the spiritual by no means, whether they remove themselves from the busy dealings of men like the turtledove, or dwell among them like the pigeon; yet both birds are simple and harmless, signifying that in the very Israelite people, to whom that land was to be given, there would be undivided peoples of promise and heirs of the kingdom remaining in eternal happiness.

Source: Commentary on Genesis
[AD 420] Jerome on Genesis 15:10-11
(Verses 10, 11.) And he placed them opposite each other: but he did not separate the birds. However, birds descended upon the carcasses and the divisions thereof, and Abram drove them away. It does not pertain to the present work to explain the sacrament. We only say this, because the Hebrew version has for these words: And birds descended upon the carcasses, and Abram drove them away. For he deservedly often delivered Israel from narrow straits.

Source: Hebrew Questions on Genesis
[AD 430] Augustine of Hippo on Genesis 15:10
And it is said, “But the birds divided he not,” because carnal people are divided among themselves. But those who are spiritual are not divided at all, whether they seclude themselves from the busy conversation of humankind, like the turtledove, or dwell among them, like the pigeon. For both birds are simple and harmless, signifying that even in the Israelite people, to which that land was to be given, there would be individuals who were children of the promise and heirs of the kingdom that is to remain in eternal felicity.

Source: City of God 16.24
[AD 542] Caesarius of Arles on Genesis 15:10
Now notice carefully Abraham is said to have divided the three animals into two parts and to have placed them one against the other. “The birds,” says Scripture, “he did not cut in two.” Why is this, brothers? Because in the church catholic, carnal people are divided but spiritual people are not. And, as Scripture says, they are separated one against the other. Why are carnal people divided and set against each other? Because all wicked lovers of the world do not cease to have divisions and scandals among each other. For this reason they are divided, since they are opposed to one another. However, the birds, that is, spiritual souls, are not divided. Why not? Because they have “one heart and one soul in the Lord.” To will and not to will is all one thing to them. Surely the turtledoves and pigeons that we mentioned above are like these souls. In the turtledove chastity is represented, and in the pigeon, simplicity. All God-fearing people in the church catholic clearly are chaste and simple, and with the psalmist they can say, “Had I but wings like a dove, I would fly away and be at rest.” And again: “The swallow finds a nest in which she puts her young.” Carnal people, who can be divided, are pressed down by the heavy fetters of vice. Spiritual people are raised on high by the wings of various virtues. As if by two wings, that is, the two precepts of love of God and charity toward the neighbor, they are lifted up to heaven. With the apostle they can say, “But our citizenship is in heaven.” As often as the priest says, “Lift up your hearts,” they can say with assurance and devotion that they have lifted them up to the Lord. However, very few and rare are the people in the church who can say this with confidence and truth. Therefore Abraham did not divide the birds, because spiritual souls who have one heart and soul, as I said, cannot be divided or separated from love of God and of neighbor. They exclaim with the apostle, “Who shall separate us from the love of Christ? Shall tribulation, or distress or persecution?” Other words follow until it is said, “Nor any other creature will be able to separate us from the love of God, which is in Christ Jesus our Lord.” Therefore spiritual souls are not separated from Christ by torments. Carnal souls are sometimes separated by idle gossip. The cruel sword cannot separate the former, but carnal affections can remove the latter. Nothing hard breaks down spiritual people, but even flattering words can corrupt the carnal. For this reason Abraham divided those animals into two parts, but the birds he did not divide.

Source: SERMON 82.2
[AD 430] Augustine of Hippo on Genesis 15:11
The fowls coming down on the divided carcasses represent nothing good but [rather] the spirits of this air, seeking some food for themselves in the division of carnal people. But that Abraham sat down with them signifies that even amid these divisions of the carnal, true believers shall persevere to the end. With the going down of the sun great fear fell upon Abraham and a horror of great darkness. This signifies that about the end of this world believers shall be in great perturbation and tribulation, of which the Lord said in the Gospel, “For then shall be great tribulation, such as was not from the beginning.”

Source: City of God 16.24
[AD 735] Bede on Genesis 15:11
And birds of prey came down upon the carcasses, and Abram drove them away. These divided birds, which descended upon the carcasses, do not indicate anything good, but rather certain spirits of this air seeking their sustenance from the division of the carnal; or certainly the carnal adversaries of the same people, who, according to the counsel of Balaam the diviner, were seeking an opportunity for victory from their crimes, concerning whom the prophet says: "Our pursuers were swifter than the eagles of the heavens" (Lamentations 4:19).

Source: Commentary on Genesis
[AD 735] Bede on Genesis 15:11
But Abram drove them away, because by his merits Israel was often delivered both from the distress of temporal evils and from the snares of evil spirits.

Source: Commentary on Genesis
[AD 398] Didymus the Blind on Genesis 15:12
As he contemplated the wonderful things of God, Abraham was struck with fear, the fear that belongs to the perfect. It will be noted … that the ecstasy came upon him “toward sunset.” The text suggests by this a progression, because the day of the present state has gone by for Abraham so that further progress might follow. Thus the blessing was extended to Abraham which says, “I will fill you with length of days,”a blessing that by no means promised him longevity but, as is quite clear, further advances in illumination.An ecstasy then fell upon him, not the ecstasy that resembles a loss of reason but that of wonder, the thrill of passing from visible to invisible things. The apostle even says, “Indeed, if we are beside ourselves, it is for God; if we are in our right mind, it is for you.” By this he means not “we are out of our minds for God” but “even if we are transported through contemplation beyond the realm of human things, we do this for God.” David likewise declares, “I said in my ecstasy: every man is a liar.” It was indeed because he was transported out of himself to participate in the divine that he said of people that they are liars, because he was no longer merely a man, by reason of his communion with the Holy Spirit. He was quite different from those of whom it is said, “While there is jealousy and strife among you, are you not of the flesh and behaving like ordinary men?” When Abraham then had been transported out of himself, a “dark fear” fell upon him, dark not by participation in darkness but in the sense of obscurity, of something whose meaning is not immediately evident. Being a “great” fear, it is not the kind that happens to the mediocre. Remember “darkness” is often used for “obscurity,” as according to this saying: “He made darkness around him his canopy.” It is indeed true that the contemplation and grasp of supernatural truths produce, even among great people, a divine vertigo and fear, and it is with some trepidation that they apply themselves to such things.

Source: ON GENESIS 230
[AD 420] Jerome on Genesis 15:12
(Verse 12) But when the sun was setting, a deep sleep fell upon Abram. The word for deep sleep in Hebrew is Thardema (), which means a descending, and we translated it as a deep sleep.

Source: Hebrew Questions on Genesis
[AD 735] Bede on Genesis 15:12
But what is added: When the sun was setting, a deep sleep fell on Abram, and a great and dark dread fell upon him, signifies the great distress and tribulation of the faithful that will occur near the end of this age. About which the Lord says in the Gospel: For then there will be great tribulation such as has not been since the beginning (Matthew 24:21).

Source: Commentary on Genesis
[AD 398] Didymus the Blind on Genesis 15:13
This word anticipates the sojourn of the people in Egypt, for they were to sojourn as it were in a land not their own. They would be reduced to slavery by the Pharaoh and mistreated in many ways by him and by the Egyptians. There is no discrepancy between what is said here and what is written in Exodus. There it is said, “After 430 years, the army of the Lord left the land of Egypt.” Here: “After four hundred years.” It should be noted that it is not said that they left when four hundred years were completed but rather after four hundred years, which leaves room for the thirty years.And the promise “I will judge the nation to which you will be enslaved” was realized in the very way described in Exodus: God afflicted the Egyptians with ten plagues, and in the end “they sank as lead in the mighty waters.” Finally, they were to leave “with much baggage,” as history would show. From this we learn that if God maltreats someone for a time, he does this not as a matter of indifference but only for some good purpose.
Consider too whether this passage might also allude to the sojourn of the saints.

Source: ON GENESIS 231
[AD 430] Augustine of Hippo on Genesis 15:13
But note what is said to Abraham, “Know of a surety that your seed shall be a stranger in a land not theirs, and they shall reduce them to servitude, and shall afflict them four hundred years.” This is most clearly a prophecy about the people of Israel, who were to be in servitude in Egypt. Not that this people was to be in that servitude under the oppressive Egyptians for four hundred years, but it is foretold that this should take place in the course of those four hundred years. It is written of Terah the father of Abraham, “And the days of Terah in Haran were 205 years,” not because they were all spent there but because they were completed there. So it is said here also, “And they shall reduce them to servitude and shall afflict them four hundred years” … because that number was completed, not because it was all spent in that affliction. The years are said to be four hundred in round numbers, although they were a little more—whether you reckon from this time when these things were promised to Abraham, or from the birth of Isaac, as the seed of Abraham, of which these things are predicted. For, as we have already said above, from the seventy-fifth year of Abraham, when the first promise was made to him, down to the exodus of Israel from Egypt, there are reckoned 430 years, which the apostle thus mentions: “And this I say, that the covenant confirmed by God, the law, which was made 430 years after, cannot disannul, that it should make the promise of no effect.” So then these 430 years might be called four hundred, because they are not much more, especially since part even of that number had already gone by when these things were shown and said to Abraham in vision, or when Isaac was born in his father’s one hundredth year, twenty-five years after the first promise, when of these 430 years there now remained 405, which God was pleased to call four hundred. No one will doubt that the other things that follow in the prophetic words of God pertain to the people of Israel.

Source: City of God 16.24
[AD 735] Bede on Genesis 15:13
And it was said to him: Know for certain that your offspring shall be strangers in a land not their own, and they will enslave them, and oppress them for four hundred years, etc. This was very clearly prophesied about the people of Israel who were to serve in Egypt. Not that this people were to be afflicted for four hundred years in the same servitude under the Egyptians who oppressed them, but it was foretold that this would happen within the four hundred years. For four hundred years are called so because of the fullness of the number, although they are somewhat more; whether computed from the time these promises were made to Abraham, or from when Isaac was born because of the offspring of Abraham of whom these promises are spoken. They are counted from Abraham's seventy-fifth year when the first promise was made to him, to the exodus of Israel from Egypt, four hundred and thirty years, of which the Apostle thus makes mention: Now this I say, says he, the covenant confirmed by God, which was made four hundred and thirty years later, does not nullify the promise (Galatians 3:17). Therefore, these four hundred and thirty years could already be called four hundred, which are not much more; how much more so when a few of this number had already passed when these things were shown and said to Abraham in a vision, or when Isaac was born to his hundred-year-old father twenty-five years after the first promise; when of those four hundred and thirty, four hundred and five remained, which the Lord wished to call four hundred.

Source: Commentary on Genesis
[AD 62] Acts on Genesis 15:14
Then said the high priest, Are these things so? And he said, Men, brethren, and fathers, hearken; The God of glory appeared unto our father Abraham, when he was in Mesopotamia, before he dwelt in Charran, And said unto him, Get thee out of thy country, and from thy kindred, and come into the land which I shall show thee. Then came he out of the land of the Chaldaeans, and dwelt in Charran: and from thence, when his father was dead, he removed him into this land, wherein ye now dwell. And he gave him none inheritance in it, no, not so much as to set his foot on: yet he promised that he would give it to him for a possession, and to his seed after him, when as yet he had no child. And God spake on this wise, That his seed should sojourn in a strange land; and that they should bring them into bondage, and entreat them evil four hundred years. And the nation to whom they shall be in bondage will I judge, said God: and after that shall they come forth, and serve me in this place. [Genesis 15:14] And he gave him the covenant of circumcision: and so Abraham begat Isaac, and circumcised him the eighth day; and Isaac begat Jacob; and Jacob begat the twelve patriarchs. And the patriarchs, moved with envy, sold Joseph into Egypt: but God was with him, And delivered him out of all his afflictions, and gave him favour and wisdom in the sight of Pharaoh king of Egypt; and he made him governor over Egypt and all his house. Now there came a dearth over all the land of Egypt and Chanaan, and great affliction: and our fathers found no sustenance. But when Jacob heard that there was corn in Egypt, he sent out our fathers first. And at the second time Joseph was made known to his brethren; and Joseph's kindred was made known unto Pharaoh. Then sent Joseph, and called his father Jacob to him, and all his kindred, threescore and fifteen souls. So Jacob went down into Egypt, and died, he, and our fathers, And were carried over into Sychem, and laid in the sepulchre that Abraham bought for a sum of money of the sons of Emmor the father of Sychem. But when the time of the promise drew nigh, which God had sworn to Abraham, the people grew and multiplied in Egypt, Till another king arose, which knew not Joseph. The same dealt subtilly with our kindred, and evil entreated our fathers, so that they cast out their young children, to the end they might not live. In which time Moses was born, and was exceeding fair, and nourished up in his father's house three months: And when he was cast out, Pharaoh's daughter took him up, and nourished him for her own son. And Moses was learned in all the wisdom of the Egyptians, and was mighty in words and in deeds. And when he was full forty years old, it came into his heart to visit his brethren the children of Israel. And seeing one of them suffer wrong, he defended him, and avenged him that was oppressed, and smote the Egyptian: For he supposed his brethren would have understood how that God by his hand would deliver them: but they understood not. And the next day he showed himself unto them as they strove, and would have set them at one again, saying, Sirs, ye are brethren; why do ye wrong one to another? But he that did his neighbour wrong thrust him away, saying, Who made thee a ruler and a judge over us? Wilt thou kill me, as thou diddest the Egyptian yesterday? Then fled Moses at this saying, and was a stranger in the land of Madian, where he begat two sons. And when forty years were expired, there appeared to him in the wilderness of mount Sina an angel of the Lord in a flame of fire in a bush. When Moses saw it, he wondered at the sight: and as he drew near to behold it, the voice of the Lord came unto him, Saying, I am the God of thy fathers, the God of Abrham, and the God of Isaac, and the God of Jacob. Then Moses trembled, and durst not behold. Then said the Lord to him, Put off thy shoes from thy feet: for the place where thou standest is holy ground. I have seen, I have seen the affliction of my people which is in Egypt, and I have heard their groaning, and am come down to deliver them. And now come, I will send thee into Egypt. This Moses whom they refused, saying, Who made thee a ruler and a judge? the same did God send to be a ruler and a deliverer by the hand of the angel which appeared to him in the bush. He brought them out, after that he had showed wonders and signs in the land of Egypt, and in the Red sea, and in the wilderness forty years.
[AD 398] Didymus the Blind on Genesis 15:15
Anyone can see that God is here announcing Abraham’s departure from this life. As for the anagogical [mystical] sense, one could say the following: The wise person leaves this life in peace, while the sinner does so with troubled thoughts and an agitated soul. And the way death takes one, so is one judged. One who has already attained peace here below takes leave also in peace. But one who has nothing but disturbance and agitation in his or her thoughts will be judged also in this way. This is clear from the saying in Ecclesiastes: “In the place where the tree falls, there it will lie.” Things do not occur this way in historical reality, because a tree does not necessarily always lie where it falls. Often it is cleared away. But it is evidently humankind who is symbolically represented by the tree, namely, a person who will be judged as he or she is found.In peace, then, as is fitting, Abraham will depart to his fathers. Being pleasing to God, he shares in their promise: “First Christ, then those who are of Christ.” And for the just themselves, there are different promises and different dwellings, because “there are many mansions” with the Father. The person full of zeal will go to be with his spiritual fathers, whose son he is through a moral likeness, even if, according to the flesh, he had fathers who were bad men.

Source: ON GENESIS 231-32
[AD 397] Ambrose of Milan on Genesis 15:16
The history of the Jews, who went down into Egypt and came out from Egypt, seems to accord with this. The years they spent there were 430, but not all of them lived a hundred years and more, as did Moses and Joshua, so that the time of the fourth generation would be appropriate in this context. So let us search rather for a mystical sense. In fact, the number four adapts well to all numbers, and it is in a certain sense the root and base of the decimal. It also represents the midpoint of the number seven. In fact, the ninety-third psalm is entitled “fourth day of the week” because this number is the intermediary between the first three and those that follow. In fact, three days precede it: the first, the second and the third; and three follow: the fifth, the sixth, the seventh. One who sings this psalm is proceeding through the life of this world, so to speak, in accordance with aptly placed numbers, like a quadrangle stable and perfect. In four books the Gospel is complete and perfect. There are four mystical animals;14 and there are also four parts of the world, from which the assembled children of the church have propagated the most holy kingdom of Christ, coming from east and west and north and south. The holy church, therefore, has arisen with four sides. The decade too derives from this number. For if you total up the numbers from one to four you will have the number ten. Count one, add two to this: this makes three. Add three to three, this makes six. And to six add four, and this makes ten. Four then generates the decade, and the decade includes all numbers. Four is also the number of ages of a man: childhood, adolescence, virility and maturity. He rises gradually, and his wisdom is consolidated. Thus the fullness of wisdom comes, considering the ages, in fourth place. For this reason even if one has formerly been subjected to the king of Egypt, nevertheless with the age of maturity he is freed from his power and acknowledges his duty to follow the law. Then the sea of this life opens up to him.

Source: ON ABRAHAM 2.9.65
[AD 398] Didymus the Blind on Genesis 15:16
After having said this of Abraham himself, God speaks of the children who will come from him: “In the fourth generation they shall come back here,” meaning the generation that would return to the land of inheritance. This is why he says that the return would take place after four hundred years, “because the iniquity of the Amorites is not yet complete”—iniquity for which they will suffer ruin, so that their condemnation will allow the descendants of Abraham to occupy their land. For God inflicts even chastisements with measure and in time, using patience until the time of retribution has arrived. There is a similar and edifying saying in the Gospel: “Then Jesus began to upbraid the cities where most of his mighty works had been done, because they did not repent: Woe to you, Chorazin! Woe to you, Bethsaida! For if the mighty works done in you had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes.” To which one might object: Why then were the miracles not done in Tyre and Sidon, because they would have repented, but were performed instead in places where the people did not repent? We would respond that the Son of God who acted in this way is Wisdom. As he knew the hidden things, he knew that these people would not have been authentically repentant, even while doing penance, and this is why the miracles did not take place among them. And one could appropriately say about these people: It was better for them not to have known the truth than, having once known it, to return to their former errors. Thus he did not do works in Tyre and Sidon, because their repentance would be fragile.… However, one might also ask whether this was not said by the Savior in a hyperbolic manner, simply to make those people reflect who had seen his miracles and had not repented, for hyperbole is a common teaching device.The patience and goodness of the judge are shown, then, in the fact that he waits until the sins of the Amorites have reached their full measure. It is only after reproaches, exhortations and everything that can provoke repentance that God inflicts chastisements. The same was true in the case of Pharaoh: often reprimanded and having obtained many reprieves, through his hardness of heart he brought upon himself the final judgment as well.

Source: ON GENESIS 232-33
[AD 420] Jerome on Genesis 15:16
(Verse 16) But in the fourth generation they will return here. There is no doubt that these will be the ones who are descended from Abraham. It is asked how it is written in Exodus: In the fifth generation the children of Israel went forth from the land of Egypt (Exodus 15:18). On this chapter, we have published a small volume.

Source: Hebrew Questions on Genesis
[AD 735] Bede on Genesis 15:16
But in the fourth generation, they shall return here. Kohath entered Egypt with his father Levi, whose son was Amram, whose son was Aaron, whose son was Eleazar, who was the fourth from Kohath. And he went out from Egypt with his father Aaron, and when he died in the wilderness, he himself entered the Promised Land.

Source: Commentary on Genesis
[AD 373] Ephrem the Syrian on Genesis 15:17
Abraham thought, “Perhaps these kings will destroy each other, or other peoples might rise up and destroy them and empty out the land for us. Perhaps my seed will become strong and will go and slay its inhabitants and possess it, or maybe the land will swallow [its inhabitants] because of their deeds. Perhaps the [inhabitants] might go into exile into another land because of hunger or rumor or some such reason.” Abraham sought to know which of these [would happen], but he had no doubts whatsoever.Then God, who knew what he sought, showed him what he did not seek in addition to what he did seek. For by the offering that Abraham made [when] the birds came down and he chased them away, God clearly showed him that his descendants would sin and be oppressed but would be saved through the prayers of their righteous ones. And by the pot of fire that came down, God made known that even if all their righteous ones should come to an end, deliverance from heaven would come to them. By the three-year-old calf and the three-year-old ram and the three-year-old goat [God showed him] that either they would be delivered after three generations or that kings, priests and prophets would soon arise from among his descendants. By the limbs of the animals that Abraham cut in two [God] depicted their many tribes, and by the bird that Abraham did not cut in two [God] signified their unity.

Source: COMMENTARY ON GENESIS 12:3
[AD 398] Didymus the Blind on Genesis 15:17-21
What is clearly stated in the text can be expounded as follows. When the sun was already near setting, a flame emerged, and there appeared a smoking oven and fiery torches “that passed between the two parts of the divided animals,” burning and lighting up the place, to allow the patriarch to see what was happening and to reveal in a more divine manner the mysteries to be searched out. It should be noted that a fire did not appear only after the covenant had been made, but the gift of the law through Moses took place itself in the midst of a fire. Fire could be seen, and, without being able to see the one who was speaking, the giving of the commandments could be heard. What is suggested here is perhaps something like this. As the law contains rewards and punishments, it was given in the midst of fire to indicate that it brings burning to some and illumination to others. In fact, fire has a twofold power: it illuminates, and at the same time it burns. The gift of the law, then, burns those who abandon it and enlightens those who observe it. So too here, torches and smoke appeared; now smoke is the result and as it were the consequence of a fire that has been lit. Moreover, a flame had appeared first. We conclude, then, that one who is defining what is to be done and what is not to be done in a matter this difficult requires the light of God and also fear, symbolized by the furnace, so as to accomplish everything in accordance with right reason.

Source: ON GENESIS 233-34
[AD 430] Augustine of Hippo on Genesis 15:17
When it is added, “And when the sun was now setting there was a flame, and lo, a smoking furnace, and lamps of fire, which passed through between those pieces,” this signifies that at the end of the world the carnal shall be judged by fire. The affliction of the city of God, such as never was before, which is expected to take place under Antichrist, was prefigured by Abraham’s horror of great darkness about the going down of the sun. When the end of the world draws nigh, so at the going down of the sun, that is, at the very end of the world, there is signified by that fire the day of judgment, which separates the carnal who are to be saved by fire from the carnal who are to be condemned in the fire. And then the covenant made with Abraham particularly sets forth the land of Canaan and names eleven tribes in it from the river of Egypt even to the great river Euphrates. It is not then from the great river of Egypt, that is, the Nile, but from a small one that separates Egypt from Palestine, where the city of Rhinocorura is.

Source: City of God 16.24
[AD 542] Caesarius of Arles on Genesis 15:17
Notice, brothers, that what is called a fiery torch passing between those pieces is also not said to have touched the turtledove and pigeon. That evening signified the end of the world. Those animals, as we already said, showed a type of all the nations who believe in Christ. Because those nations have in them not only spiritual people, as was already said, that is, not only good people but even the wicked, for this reason the animals were divided and the fiery torch passed through them. According to what the apostle says, “The day of the Lord will declare it, since it will be revealed in fire,” and so forth. That burning, smoking oven and fiery torch prefigured the day of judgment, and for this reason fear and a darksome horror settled upon blessed Abraham. Therefore we have realized that “if the just man scarcely will be saved,” on the day of judgment, “where will the impious and the sinner appear?” That burning, smoking oven signified judgment day: the day of judgment, I repeat, on which “there will be the weeping and the gnashing of teeth.” On that day there will be wailing and lamenting and repentance that is too late, when the foundations of the mountains will be moved and the earth will burn down to hell.

Source: SERMON 82.3
[AD 542] Caesarius of Arles on Genesis 15:17
Therefore, in order that we may not come to this torture of soul, let us awake while there is time for correction and like good, profitable servants seek the will of our Lord. Then when that dreadful day of judgment comes, which is dreaded exceedingly even by the good and was signified by that burning, smoking oven, we will not be tormented in hell by avenging flames in company with carnal people. These souls were signified by the animals, because they can be divided by various contentious desires. Let us rather show the simplicity of the pigeon and the chastity of the turtledove, so that we may be raised to heaven on the spiritual wings of virtue. According to the apostle’s words, “We shall be caught up together with them in clouds to meet the Lord in the air, and so we shall ever be with the Lord” with the help of our Lord Jesus Christ, to whom is honor and glory together with the Father and the Holy Spirit world without end. Amen.

Source: SERMON 82.3
[AD 735] Bede on Genesis 15:17
So when the sun had set, a dense darkness came over, and a smoking furnace appeared, and a blazing torch passed between the pieces. This darkness and the fire furnace occurring after the sunset signifies that at the end of the world, the carnal will be judged by fire. For just as the affliction of the City of God, such as never was before and is expected to come under the Antichrist, is signified by the frightening darkness upon Abraham at sunset, that is, as the end of the age approaches; so at sunset, that is, at the end itself, it is signified by this fire that the day of judgment will save the carnal through fire and condemn them in fire.

Source: Commentary on Genesis
[AD 397] Ambrose of Milan on Genesis 15:18-19
Foreign peoples are given to Abraham as though for education and so that the most scrupulous mind of the just person might cut away their vices and correct their errors. But what is most evident here is rather the mystery of the church. Through its apostles, “who are Israelites, to whom belong the patriarchs,” and from whose patriarchs “Christ was born according to the flesh” under the law, the church was to be constituted from the gathering of pagan peoples who would believe. And it is not by accident that these are indicated by the number ten but rather to show that these, at first unbelievers, when they had completed the measure of impiety, would certainly obtain the crown of faith.

Source: ON ABRAHAM 2.10.71
[AD 398] Didymus the Blind on Genesis 15:18-19
When the torches had passed over the divided animals, the covenant was made. God said to Abraham, “To your descendants I will give this land,” and he described in detail how far the land extended in each direction. But, through an anagogical [mystical] transposition consistent with our above remarks, we must understand that this land is given to the holy man’s spiritual posterity. The Savior too promises it to those who practice gentleness. This is a promise that applies to the true children and not to all who descend from Abraham, for “it is not the children of the flesh who are the children of God, but the children of the promise are reckoned as descendants.” It is “the one who does the works of Abraham” who is in fact his child.The phrase “from the river to the river” is also well put, for the promise that belongs to the posterity of the holy man is virtue, which is placed between flowing things. Flowing things, of course, do not make up virtue but are its very borders, in the sense that if one departs from virtue, one encounters them immediately. But it is possible too that the rivers represent the trials that come to virtuous persons, since they are placed among people who oppress them, and yet the virtuous triumph over them.

Source: ON GENESIS 234
[AD 735] Bede on Genesis 15:18
On that day, the Lord made a covenant with Abram, saying: To your descendants, I will give this land, from the river of Egypt to the great river Euphrates. The river of Egypt, which is the Nile, he does not call great but small, which separates Egypt and Palestine, where the city of Rhinocorura is. Therefore, the Lord made a covenant with Abram on that day, when he offered the sacrifices of animals and birds. Certainly, that covenant was that he and his descendants would always offer prayers and sacrifices to the Lord with a faithful heart; and the Lord in turn would grant him and his descendants the land of Canaan to possess forever.

Source: Commentary on Genesis