Numbers 8:18-20

Revised Standard Version

¹⁸ and I have taken the Levites instead of all the first-born among the people of Israel. ¹⁹ And I have given the Levites as a gift to Aaron and his sons from among the people of Israel, to do the service for the people of Israel at the tent of meeting, and to make atonement for the people of Israel, that there may be no plague among the people of Israel in case the people of Israel should come near the sanctuary.”

²⁰ Thus did Moses and Aaron and all the congregation of the people of Israel to the Levites; according to all that the Lord commanded Moses concerning the Levites, the people of Israel did to them.