Hebräer 5:4

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 sin of Korah was, not content with the ministry as a Levite, he took the sacerdotal priesthood also. No Christian minister, as such, is ever called Hiereus, that is, sacrificing priest. All Christians, without distinction, whether ministers or people, have a metaphorical, not a literal, priesthood. The sacrifices which they offer are spiritual, not literal, their bodies and the fruit of their lips, praises continually (Heb 13:15). Christ alone had a proper and true sacrifice to offer. The law sacrifices were typical, not metaphorical, as the Christian's, nor proper and true, as Christ's. In Roman times the Mosaic restriction of the priesthood to Aaron's family was violated.

In this chapter the apostle continues his discourse upon the priesthood of Christ, a sweet subject, which he would not too soon dismiss. And here, I. He explains the nature of the priestly office in general (Heb 5:1-3). II. The proper and regular call there must be to this office (Heb 5:4-6). III. The requisite qualifications for the work (Heb 5:7-9). IV. The peculiar order of the priesthood of Christ; it was not after the order of Aaron, but of Melchisedec (Heb 5:6, Heb 5:7, Heb 5:10). V. He reproves the Hebrews, that they had not made those improvements in knowledge which might have made them capable of looking into the more abstruse and mysterious parts of scripture (Heb 5:11-14).

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).