Numbers 8:12-14

American Standard Version

¹² And the Levites shall lay their hands upon the heads of the bullocks: and offer thou the one for a sin-offering, and the other for a burnt-offering, unto Jehovah, to make atonement for the Levites. ¹³ And thou shalt set the Levites before Aaron, and before his sons, and offer them for a wave-offering unto Jehovah.

¹⁴ Thus shalt thou separate the Levites from among the children of Israel; and the Levites shall be mine.