Hebrews 5:4

“And no man taketh this honour to himself, etc..] That is, the honour of the priesthood: the office of the high priest was a very honourable one; it was a peculiar honour to Aaron, and his sons, to be separated unto it; their instalment into it was very grand and solemn; at that time they were anointed with oil, and clothed with glorious garments, and sacrifices were offered for them; they had an honourable maintenance assigned them, and a large retinue of priests and Levites to attend them; great respect and reverence were shown them: but their principal honour lay in the work they performed; in representing the whole body of the people; in offering gifts and sacrifices for them; in blessing…”

“no man--of any other family but Aaron's, according to the Mosaic law, can take to himself the office of high priest. This verse is quoted by some to prove the need of an apostolic succession of ordination in the Christian ministry; but the reference here is to the priesthood, not the Christian ministry. The analogy in our Christian dispensation would warn ministers, seeing that God has separated them from the congregation of His people to bring them near Himself, and to do the service of His house, and to minister (as He separated the Levites, Korah with his company), that content with this, they should beware of assuming the sacrificial priesthood also, which belongs to Christ alone. The…”

“And no man taketh this honor to himself - No one has a right to enter on this office unless he has the qualifications which God has prescribed. There were fixed and definite laws in regard to the succession in the office of the high priest, and to the qualifications of him who should hold the office. But he that is called of God as was Aaron - Aaron was designated by name. It was necessary that his successors should have as clear evidence that they were called of God to the office, as though they had been mentioned by name. The manner in which the high priest was to succeed to the office was designated in the Law of Moses, but in the time of Paul these rules were little regarded. The office…”

“The apostle begins here to treat of the priesthood of Christ. The sum of what he observes concerning it is, Whatever is excellent in the Levitical priesthood is in Christ, and in a more eminent manner; and whatever is wanting in those priests is in him. And no one taketh this honour - The priesthood. To himself, but he that is called of God, as was Aaron - And his posterity, who were all of them called at one and the same time. But it is observable, Aaron did not preach at all; preaching being no part of the priestly office. Hebrews 5:5”

“5:4 The role of high priest is by God’s appointment rather than human enlistment (see Exod 28:1; Lev 8:1-12; Num 16:1-26).”

“Exo 28:1; Lev 8:2; Num 3:3, Num 16:5, Num 16:7, Num 16:10, Num 16:35, Num 16:40, Num 16:46-48, Num 17:3-11, Num 18:1-5; Ch1 23:13; Ch2 26:18; Joh 3:27 Hebrews 5:5”