Numbers 8:20-22

20Moses, Aaron, and the entire Israelite community did this to the Levites. The Israelites did everything to them the Lord commanded Moses regarding the Levites.

21The Levites purified themselves and washed their clothes; then Aaron presented them before the Lord as a presentation offering. Aaron also made atonement for them to cleanse them ceremonially.

22After that, the Levites came to do their work at the tent of meeting in the presence of Aaron and his sons. So they did to them as the Lord had commanded Moses concerning the Levites.