Exodus 29:9-11

And thou shalt gird them with girdles, Aaron and his sons, and bind head-tires on them: and they shall have the priesthood by a perpetual statute: and thou shalt consecrate Aaron and his sons. And thou shalt bring the bullock before the tent of meeting: and Aaron and his sons shall lay their hands upon the head of the bullock. And thou shalt kill the bullock before Jehovah, at the door of the tent of meeting.