Exodus 29:8-11

8You shall also bring his sons and put 1tunics on them. 9And you shall wrap their waists with 2sashes, Aaron and his sons, and fit 3caps on them, and they shall have 4the priesthood by a permanent statute. So you shall 56ordain Aaron and his sons.

10“Then you shall bring the bull in front of the tent of meeting, and Aaron and his sons shall 7lay their hands on the head of the bull. 11And you shall slaughter the bull before the Lord at the doorway of the tent of meeting.