Numbers 18:5

2 Let your brothers, the family of Levi, come near with you, so that they may be joined with you and be your servants: but you and your sons with you are to go in before the ark of witness.

3 They are to do your orders and be responsible for the work of the Tent; but they may not come near the vessels of the holy place or the altar, so that death may not overtake them or you.

4 They are to be joined with you in the care of the Tent of meeting, doing whatever is needed for the Tent: and no one of any other family may come near you.

5 You are to be responsible for the holy place and the altar, so that wrath may never again come on the children of Israel.

6 Now, see, I have taken your brothers the Levites from among the children of Israel: they are given to you and to the Lord, to do the work of the Tent of meeting.

7 And you and your sons with you are to be responsible as priests for the altar and everything on it, and everything inside the veil; you are to do the work of priests; I have given you your position as priests; and any other man who comes near will be put to death.

8 And the Lord said to Aaron, See, I have given into your care my lifted offerings; even all the holy things of the children of Israel I have given to you and to your sons as your right for ever, because you have been marked with the holy oil.