Numbers 8:14

¹²And the Levites shall lay their hands on the heads of the calves; and thou shalt offer one for a sin offering, and the other for a whole burnt offering to the Lord, to make atonement for them.

¹³And thou shalt set the Levites before the Lord, and before Aaron, and before his sons; and thou shalt give them as a gift before the Lord.

— Numbers 8:14 —

¹⁵And afterward the Levites shall go in to perform the works of the tabernacle of witness; and thou shalt purify them, and present them before the Lord.

¹⁶For these are given to me for a present out of the midst of the children of Israel: I have taken them to myself instead of all the firstborn of the sons of Israel that open every womb.