Numbers 3:7-8

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.

Numbers 3:10

3:10 So you are to appoint Aaron and his sons, and they will be responsible for their priesthood; but the unauthorized person who comes near must be put to death.”