Numbers 8:12

And the Levites are to lay their hands on the heads of the bulls, and offer to the LORD one as a sin offering and the other as a burnt offering, to make atonement for the Levites.

And the Levites shall lay their hands upon the heads of the bullocks: and thou shalt offer the one for a sin offering, and the other for a burnt offering, unto the LORD, to make an atonement for the Levites.