Hebrews 5:1-5 NKJV
For every high priest taken from among men is appointed for men in things pertaining to God, that he may offer both gifts and sacrifices for sins. He can have compassion on those who are ignorant and going astray, since he himself is also subject to weakness. Because of this he is required as for the people, so also for himself, to offer sacrifices for sins. And no man takes this honor to himself, but he who is called by God, just as Aaron was.
So also Christ did not glorify Himself to become High Priest, but it was He who said to Him:
“You are My Son,
Today I have begotten You.”
NKJV: New King James Version