Numbers 6:11

6:11 Then the priest will offer one for a purification offering and the other as a burnt offering, and make atonement for him, because of his transgression in regard to the corpse. So he must reconsecrate his head on that day.

Numbers 8:12

8:12 When the Levites lay their hands on the heads of the bulls, offer the one for a purification offering and the other for a whole burnt offering to the Lord, to make atonement for the Levites.