Numbers 8:20-26 - The Levites Are Dedicated To The Lord
20 And Moses and Aaron and the entire community of the {Israelites} did to the Levites; everything that Yahweh commanded Moses concerning the Levites, the {Israelites} did to them. 21 And the Levites purified themselves, and they washed their garments, and {Aaron offered them} [as] a wave offering {before Yahweh}; and Aaron made atonement for them to purify them. 22 After this the Levites came to do their work in the tent of assembly before Aaron and his sons. Just as Yahweh commanded Moses concerning the Levities, so they did to them.
23 Yahweh spoke to Moses, saying, 24 "This [is] what is for the Levites: {those twenty-five years old} and above will come to help [with the] service in the work of the tent of assembly; 25 and {those fifty years old} will return from the service of the work and will serve no longer. 26 They can attend their brothers in the tent of assembly to keep [their] responsibilities, but they will not do work. This is what you will do concerning the Levities and their responsibilities."