Numbers 8:13-15

New Revised Standard Version Catholic Edition

¹³ Then you shall have the Levites stand before Aaron and his sons, and you shall present them as an elevation offering to the Lord.

¹⁴ Thus you shall separate the Levites from among the other Israelites, and the Levites shall be mine. ¹⁵ Thereafter the Levites may go in to do service at the tent of meeting, once you have cleansed them and presented them as an elevation offering.