Hebrews 5:1, 3, 6, 10, 12

For every high priest, being taken from among men, is appointed for men in things pertaining to God, that he may offer both gifts and sacrifices for sins

and by reason thereof is bound, as for the people, so also for himself, to offer for sins.

as he saith also in another place, Thou art a priest for ever After the order of Melchizedek.

named of God a high priest after the order of Melchizedek.

For when by reason of the time ye ought to be teachers, ye have need again that some one teach you the rudiments of the first principles of the oracles of God; and are become such as have need of milk, and not of solid food.