Exodus 29:8-11

8You are to present his sons and clothe them with tunics

9and wrap the sashes around Aaron and his sons and put headbands on them, and so the ministry of priesthood will belong to them by a perpetual ordinance. Thus you are to consecrate Aaron and his sons.

10“You are to present the bull at the front of the tent of meeting, and Aaron and his sons are to put their hands on the head of the bull.

11You are to kill the bull before the Lord at the entrance to the tent of meeting