Numbers 8:17-21
English Standard Version
Chapter 8
17For all the firstborn among the people of Israel are mine, both of man and of beast. On the day that I struck down all the firstborn in the land of Egypt I consecrated them for myself, 18and I have taken the Levites instead of all the firstborn among the people of Israel. 19And 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 when the people of Israel come near the sanctuary."
20Thus 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.
21And the Levites purified themselves from sin and washed their clothes, and Aaron offered them as a wave offering before the Lord, and Aaron made atonement for them to cleanse them.
