Numbers 3:6-16
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.
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.”
3:11 Then the Lord spoke to Moses:
3:12 “Look, I myself have taken the Levites from among the Israelites instead of every firstborn who opens the womb among the Israelites. So the Levites belong to me,
3:13 because all the firstborn are mine. When I destroyed all the firstborn in the land of Egypt, I set apart for myself all the firstborn in Israel, both man and beast. They belong to me. I am the Lord.”
The Numbering of the Levites
3:14 Then the Lord spoke to Moses in the wilderness of Sinai:
3:15 “Number the Levites by their clans and their families; every male from a month old and upward you are to number.”
3:16 So Moses numbered them according to the word of the Lord, just as he had been commanded.