Numbers 3:6-9

3:6 “Bring the tribe of Levi near, and present them before Aaron the priest, that they may serve him. 3:7 They are responsible for his needs and the needs of the whole community before the tent of meeting, by attending to the service of the tabernacle. 3:8 And they are responsible for all the furnishings of the tent of meeting, and for the needs of the Israelites, as they serve in the tabernacle. 3:9 You are to assign the Levites to Aaron and his sons; they will be assigned exclusively to him out of all the Israelites.