1 And the LORD spake unto Moses, saying, 2 Speak unto the children of Israel, and take of every one of them a rod according to the house of their fathers, of all their princes according to the house of their fathers twelve rods: write thou every man's name upon his rod. 3 And thou shalt write Aaron's name upon the rod of Levi: for one rod shall be for the head of the house of their fathers. 4 And thou shalt lay them up in the tabernacle of the congregation before the testimony, where I will meet with you. 5 And it shall come to pass, that the man's rod, whom I shall choose, shall blossom: and I will make to cease from me the murmurings of the children of Israel, whereby they murmur against you. 6 And Moses spake unto the children of Israel, and every one of their princes gave him a rod apiece, for each prince one, according to their fathers' houses, even twelve rods: and the rod of Aaron was among their rods. 7 And Moses laid up the rods before the LORD in the tabernacle of witness. 8 And it came to pass, that on the morrow Moses went into the tabernacle of witness; and, behold, the rod of Aaron for the house of Levi was budded, and brought forth buds, and bloomed blossoms, and yielded almonds. 9 And Moses brought out all the rods from before the LORD unto all the children of Israel: and they looked, and took every man his rod. 10 And the LORD said unto Moses, Bring Aaron's rod again before the testimony, to be kept for a token against the rebels; and thou shalt quite take away their murmurings from me, that they die not. 11 And Moses did so: as the LORD commanded him, so did he. 12 And the children of Israel spake unto Moses, saying, Behold, we die, we perish, we all perish. 13 Whosoever cometh any thing near unto the tabernacle of the LORD shall die: shall we be consumed with dying?
[AD 407] John Chrysostom on Numbers 17:2
We can also learn from other sources how awesome was the dignity of the priesthood. Indeed, there was a day when some wicked and evil men revolted against Aaron, quarreled with him over his position in the community and tried to drive him from his leadership. Moses, the mildest of men, wanted to persuade them by the facts themselves that he had not brought Aaron to the leadership because he was a brother, relative or member of his family but that it was in obedience to God’s decree that he had entrusted the priesthood to him. So he ordered each tribe to bring a staff, and Aaron was instructed to do the same.When each tribe had brought a staff, Moses took all of them and put them inside the meeting tent. Once he had put them there, he gave orders that they await the decision of God which would come to them through those staves. Then all the other staves kept their same appearance, but a single one—Aaron’s—blossomed and put forth leaves and fruit. So the Lord of nature used leaves instead of letters to teach them that he had again elected Aaron.

[AD 397] Ambrose of Milan on Numbers 17:8
In the book of the prophet Scripture says, “Take up for yourself a rod from a nut tree.” Consider the reason why the Lord said this to the prophet. For indeed, what was written is not inconsequential, since also in the Pentateuch we read that the priest Aaron’s staff, cut from a nut tree, blossomed when it had been put away for some time. Now it seems to mean that prophetic or priestly authority ought to be direct, so that it urges not so much what is enjoyable as what is beneficial.

[AD 397] Ambrose of Milan on Numbers 17:8
For that reason, too, [God] himself chose Aaron as priest, in order that not human cupidity but the grace of God would be the preponderant force in choosing the priest. It would not be a voluntary offering or one’s own assumption but a heavenly vocation. The one who can suffer on behalf of sinners may offer gifts on behalf of sins, because “even he himself,” Scripture says, “bears infirmity.” No one should assume the honor for himself but be called by God, just as Aaron was. In this way even Christ did not claim the priesthood but received it.

[AD 397] Ambrose of Milan on Numbers 17:8
Paul came to preach the cross of the Lord, an oak that is always verdant. And almonds appear, which are rather hard in shell but more tender in meat—it was right that Aaron’s priestly rod was of the almond tree, and Jeremiah’s staff as well—and double money too. Who would doubt that these gifts were useful? For the life of the patriarch and the preaching of the apostle are always verdant in the heart of each man, and the speech of the saints shines brightly with the splendor of the precepts of salvation, like silver tried by the fire. And it is with reason that they carry double money, for in them there is prefigured the coming of Paul, who presented presbyters who labor in the word and in the teaching with a double honor.

[AD 542] Caesarius of Arles on Numbers 17:8
There is only one true high priest, as Scripture says, of whom the high priest Aaron presented a figure. For this reason his rod blossomed. Just as Aaron’s rod sprouted among the Jewish people, so the cross of Christ flowered among the Gentiles. However, since Christ is the true high priest, as we have often said, he is the only one whose rod of the cross not only sprouted but also blossomed and produced the fruit of all believers.What is the fruit which it bore? “Ripe almonds.” Almonds are nuts, brethren. This fruit is bitter indeed in its first covering, is protected and defended by the second, but in the third part [it] feeds and nourishes whoever eats it. Such then is knowledge of the law and the prophets in Christ’s church. The first appearance of the letter is quite bitter, because it commands circumcision of the flesh, enjoins sacrifices and ordains other things which are designated as the killing letter. Throw away all these things as the bitter shell of the nut. In the second place, you will come to the protective covering, in which is indicated moral doctrine or the idea of self-restraint. This is necessary for the protection of what is kept inside but doubtless must sometimes be broken and destroyed. For example, fasting and chastisement of the body are no doubt necessary as long as we are in this corruptible body which is subject to suffering. However, when it has been destroyed and dissolved at the approach of death, it will become incorruptible at the time of the resurrection when it has been restored from corruption, spiritual after being natural, and without any flattery to the body will dominate, with no difficult suffering or propitiatory fasting but by its own nature. Thus then that rather hard covering of the nut seems to be a means of self-control at present that will not be sought later. Third, you will find hidden as in the nut the secret meaning of the mysteries of God’s wisdom and knowledge. With these, holy souls are nourished and fed not only in the present life but also in the future one. This is that priestly fruit concerning which it is promised to those “who hunger and thirst for justice, for they shall be satisfied.”

[AD 1781] Richard Challoner on Numbers 17:8
The rod of Aaron for the house of Levi, was budded: This rod of Aaron which thus miraculously brought forth fruit, was a figure of the blessed Virgin conceiving and bringing forth her Son without any prejudice to her virginity.