Hebrews 5:1-4

Every high priest is selected from among the people and is appointed to represent the people in matters related to God, to offer gifts and sacrifices for sins. He is able to deal gently with those who are ignorant and are going astray, since he himself is subject to weakness. This is why he has to offer sacrifices for his own sins, as well as for the sins of the people. And no-one takes this honour on himself, but he receives it when called by God, just as Aaron was.