Numbers 3:5-13

5Then the Lord said to Moses,

6“Call forward the tribe of Levi, and present them to Aaron the priest to serve as his assistants.

7They will serve Aaron and the whole community, performing their sacred duties in and around the Tabernacle.

8They will also maintain all the furnishings of the sacred tent, serving in the Tabernacle on behalf of all the Israelites.

9Assign the Levites to Aaron and his sons. They have been given from among all the people of Israel to serve as their assistants.

10Appoint Aaron and his sons to carry out the duties of the priesthood. But any unauthorized person who goes too near the sanctuary must be put to death.”

11And the Lord said to Moses,

12“Look, I have chosen the Levites from among the Israelites to serve as substitutes for all the firstborn sons of the people of Israel. The Levites belong to me,

13for all the firstborn males are mine. On the day I struck down all the firstborn sons of the Egyptians, I set apart for myself all the firstborn in Israel, both of people and of animals. They are mine; I am the Lord.”