Numbers 18:3

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.

Numbers 18:7

18:7 But you and your sons with you are responsible for your priestly duties, for everything at the altar and within the curtain. And you must serve. I give you the priesthood as a gift for service; but the unauthorized person who approaches must be put to death.”