Exodus 29:7-11

Then you shall take the anointing oil and pour it on his head, and anoint him.

You shall also bring his sons and put tunics on them.

And you shall wrap their waists with sashes, Aaron and his sons, and fit caps on them, and they shall have the priesthood by a permanent statute. So you shall ordain Aaron and his sons. The Sacrifices

“Then you shall bring the bull in front of the tent of meeting, and Aaron and his sons shall lay their hands on the head of the bull.

And you shall slaughter the bull before the Lord at the doorway of the tent of meeting.