9 And if thine eye offend thee, pluck it out, and cast it from thee: it is better for thee to enter into life with one eye, rather than having two eyes to be cast into hell fire.
[AD 253] Origen of Alexandria on Matthew 18:7-9
This we may understand not of the material elements of the world; but here the men who are in the world, are called the worlda. But Christ's disciples are not of this world, whence there cannot be woe to them from offences; for though there be many offences, they do not touch him who is not of this world. But if he be yet of this world in loving the world, and the things in it, as many offences will seize him as those by which he was encompassed in the world. It follows, For it must needs be that offences come.

Or; The scandals that are to come are the Angels of Satan. But do not look that these offences should show themselves in a substantial or natural shape, for in some the freedom of the will has been the origin of offence, not liking to undergo toil for virtue's sake. But there cannot be real good, without the opposition of evil. It must needs be then that offences come, as it must needs be that we encounter the evil assaults of spiritual powers; whose hatred is the more stirred up, as Christ's word invading men drives out the evil influences from them. And they seek instruments by whom the offences may the rather work; and to such instruments is more woe; for him who gives, it shall be worse than for him who takes, the offence, as it follows, But woe unto that man by whom the offence cometh.

Or, The priests may with good reason be called the eyes of the Church, since they are considered her watchmen, but the deacons and the rest her hands, for by them spiritual deeds are wrought; the people are the feet of the body, the Church; and all these it behoves not to spare, if they become an offence to the Church. Or, by the offending hand is understood an act of the mind; a motion of the mind is the offending foot, and a vision of the mind is the sinning eye, which we ought to cut off if they give offence, for thus the acts of the limbs are often put in Scripture for the limbs themselves.

[AD 367] Hilary of Poitiers on Matthew 18:7-9
Or; The lowliness of His passion is the scandal of the world, which refused to receive the Lord of eternal glory under the disgrace of the Cross. And what more dangerous for the world than to have rejected Christ? And He says that offences must needs come, forasmuch as in the sacrament of restoring to us eternal life, all lowliness of suffering was to be fulfilled in Him.

Or; By the man is denoted the Jewish people, as the introducers of all this offence that is about Christ's passion; for they brought upon the world all the danger of denying Christ in His passion, of whom the Law and the Prophets had preached that He should suffer.

[AD 407] John Chrysostom on Matthew 18:7-9
(Hom. lix.) This does not subvert the liberty of the will, or impose a necessity of any act, but foreshews what must come to pass. Offences are hindrances in the right way. But Christ's prophecy does not bring in the offences, for it is not done because He foretold it, but He foretold it because it was certainly to come to pass. But some one will say, If all men are recovered, and if there be none to bring the offences, will not His speech be convicted of falsehood? By no means; for seeing that men were incurable, He therefore said, It must needs he that offences come; that is, they surely will come; which He never would have said, if all men might be amended.

For offences rouse men, and make them more attentive; and he who falls by them speedily rises again, and is more careful.

But that you may learn that there is no absolute necessity for offences, hear what follows, If thy hand or thy foot offend thee, & c. This is not said of the limbs of the body, but of friends whom we esteem as limbs necessary to us; for nothing is so hurtful as evil communications.

[AD 420] Jerome on Matthew 18:7-9
As much as to say, Woe to that man through whose fault it comes to pass, that offences must needs be in the world. And under this general declaration, Judas is particularly condemned, who had made ready his soul for the act of betrayal.

So all affection, our whole kindred, are severed from us; lest under cover of duty any believer should be exposed to offence. If, He says, he be united to thee as close as is thy hand, or foot, or eye, and is useful to thee, anxious and quick to discern, and yet causes thee offence, and is by the unmeetness of his behaviour drawing thee into hell; it is better for thee that thou lack his kindred, and his profitableness to thee, than that whilst thou seekest to gain thy kindred or friends, thou shouldest have cause of fallings. For every believer knows what is doing him harm, what troubles and tempts him, for it is better to lead a solitary life, than to lose eternal life, in order to have the things necessary for this present life.

[AD 430] Augustine of Hippo on Matthew 18:7-9
(Quæst. Ev. i. 24) Otherwise; Whoso offendeth one of these little ones, that is so humble as He would have his disciples to be, by not obeying, or by opposing, (as the Apostle says of Alexander,) it were better for him, that a millstone should be hanged about his neck, and he be drowned in the depths of the sea, (2 Tim. 4:15.) that is, it were better for him that desire of the things of the world, to which the blind and foolish are tied down, should sink him by its load to destruction.

[AD 856] Rabanus Maurus on Matthew 18:7-9
Scandal (offence) is a Greek word, which we may call a stumbling-block, or a fall, or hitting of the foot. He then scandalizes his brother, who by word or deed amiss gives him occasion of falling.

[AD 1274] Glossa Ordinaria on Matthew 18:7-9
(non occ.) The Lord had said, that it is better for him who gives offence, that a mill-stone be hanged about his neck, of which He now subjoins the reason, Woe unto the world from offences! i. e. because of offences.

(interlin. 1 Cor. 11:19.) Or they must needs come because they are necessary, that is, useful, that by this mean they that are approved may be made manifest.

[AD 420] Jerome on Matthew 18:8-9
(Verse 8, 9) But if your hand or your foot causes you to stumble, cut it off and throw it away. It is better for you to enter life maimed or crippled than to have two hands or two feet and be thrown into the eternal fire. And if your eye causes you to stumble, gouge it out and throw it away. It is better for you to enter life with one eye than to have two eyes and be thrown into the fire of hell. Indeed, it is necessary for scandals to come, but woe to the person through whom the scandal comes! Therefore, every affection is cut off and every proximity is amputated, so that no one of the believers may be exposed to scandals through the opportunity of piety. If, he says, someone is so connected to you like a hand, foot, eye, and is useful and caring, and sharp in discerning: but he causes scandal to you, and he drags you into hell because of the disparity of his behavior: it is better that you both avoid his proximity and carnal benefits, so that while you want to profit your relatives and necessary ones, you don't end up causing ruins. Therefore, neither brother, nor wife, nor children, nor friends, nor any affection that can exclude us from the kingdom of heaven, should be preferred to the love of the Lord. Each believer knows what harms themselves, what troubles their soul, and is often tested. It is better to lead a solitary life than to lose eternal life for the needs of this present life.

[AD 500] Desert Fathers on Matthew 18:8-9
A brother asked Poemen, ‘What is the meaning of the text, “Whoever is angry with his brother without a cause” (Matt. 5:22)?’ He answered, ‘If you are angry with your brother for any kind of trouble that he gives you, that is anger without a cause, and it is better to pluck out your right eye and cast it from you. But if anyone wants to separate you from God, then you must be angry with him.’

[AD 253] Origen of Alexandria on Matthew 18:9
If somebody, in the whole body of the congregations of the church, is industrious and handy for practical action and he changes and his hand causes him to sin, the eye should say to this hand, “I have no need of you.” And after it has said it, let him cut it off and throw it from him. All will still be well if his head is still blessed and his feet worthy of his blessed head, so that the head, doing its duty, may not be able to say to the feet, “I have no need of you.” But if some foot is found which is a temptation to sin for the whole body, the head should say to this foot, “I have no need of you,” and should cut it off and throw it away from him. It is far better for the rest of the body to go on into life lacking the foot or hand that offers temptation to sin than for the whole body to be exposed to temptation and to be sent into eternal fire with two whole feet or hands. Likewise it is good if what could be the eye of the whole body shows itself worthy of Christ and of the whole body. But if at some time it happens that this eye so changes that it becomes a temptation to sin for the whole body, it will be better for it to be ripped out and thrown from the whole body … than for the whole body together with the soul to be condemned.

[AD 406] Chromatius of Aquileia on Matthew 18:9
This sentence of the Lord can faithfully be understood about any one of us. Yet in cutting off a hand or foot or in plucking out an eye, it is clear that family relations or unbelieving ministers and leaders of the church are signified.And so by “hand” we understand that priests are signified; like a hand their work in every area is necessary to the body of the church, about whom we find it written in the Song of Solomon: “his arms”—that is, the body of the church—“are rounded gold set with jewels.” By “foot” we recognize that deacons are signified. In busying themselves with the sacred mysteries of the church they serve the body like feet, about which it is written in the same Song of Solomon: “His legs are alabaster columns, set upon bases of gold.” And so, if hands or feet of this sort, that is, any priest or deacon, either through heretical faith or through depraved living, has become a stumbling block to the church, the Lord orders that such a man be plucked from the body of the church and thrown out. The example of his life and heretical doctrine endangers all the body of the church, that is, the whole people, when it follows or imitates such doctrine.

[AD 1107] Theophylact of Ohrid on Matthew 18:9
. Hand, foot, and eye understand to mean friends whom we rank as dear as our own members. And even though it may be these, our close friends, who harm us, we must disregard them as gangrenous members and cut them off, lest they harm others as well as themselves. From this it is clear that even if it is necessary that temptations come, that is, those who would harm us, it is not necessary that we be harmed. But if we shall do as the Lord has said, and cut off from ourselves those that would harm us even though they are our friends, we shall not be harmed.
[AD 1274] Glossa Ordinaria on Matthew 18:9
Interlin.: Or they must needs come because they are necessary, that is, useful, that by this mean “they that are approved may be made manifest.”