Numbers 8:8-12

8“Then they are to take a young bull with its grain offering of fine flour mixed with oil, plus a second young bull for a sin offering.

9Bring the Levites before the Tent of Meeting, and gather the whole community of Bnei-Yisrael.

10Bring the Levites before Adonai, Bnei-Yisrael will lay their hands on the Levites,

11and Aaron will present the Levites before Adonai as a wave offering from Bnei-Yisrael. Then they may go about the work of the service of Adonai.

12“The Levites are to lay their hands on the heads of the bulls. Use one for a sin offering and the other for a burnt offering to Adonai to make atonement for the Levites.