Numbers 18:1-6
Responsibilities of the Priests
18:1 The Lord said to Aaron, “You and your sons and your tribe with you must bear the iniquity of the sanctuary, and you and your sons with you must bear the iniquity of your priesthood.
18:2 “Bring with you your brothers, the tribe of Levi, the tribe of your father, so that they may join with you and minister to you while you and your sons with you are before the tent of the testimony.
18:3 They must be responsible to care for you and to care for the entire tabernacle. However, they must not come near the furnishings of the sanctuary and the altar, or both they and you will die.
18:4 They must join with you, and they will be responsible for the care of the tent of meeting, for all the service of the tent, but no unauthorized person may approach you.
18:5 You will be responsible for the care of the sanctuary and the care of the altar, so that there will be no more wrath on the Israelites.
18:6 I myself have chosen your brothers the Levites from among the Israelites. They are given to you as a gift from the Lord, to perform the duties of the tent of meeting.