Numbers 8:19-21

New Catholic Bible

¹⁹ I have given the Levites as a gift to Aaron and his sons from among the people of Israel, to perform the work of the people of Israel in the tent of meeting and to make atonement for the people of Israel, so that no plague may come upon the people of Israel when the people of Israel approach near the sanctuary.”

²⁰ So Moses and Aaron and all the assembly of the people of Israel did to the Levites what God had commanded Moses concerning the Levites, that is what the people of Israel did to them. ²¹ The Levites purified themselves and washed their clothes. Aaron presented them as a wave offering to the Lord, and made atonement for them to purify them.