Exodus 29:9-11

Wrap the sashes around the waists of Aaron and his sons, and put their special head coverings on them. Then the right to the priesthood will be theirs by law forever. In this way, you will ordain Aaron and his sons. “Bring the young bull to the entrance of the Tabernacle, where Aaron and his sons will lay their hands on its head. Then slaughter the bull in the LORD’s presence at the entrance of the Tabernacle.