Numbers 4:18

16“The duty of Eleazar the son of Aaron the priest shall be the oil for the light, the sweet incense, the continual meal offering, and the anointing oil, the requirements of all the tabernacle, and of all that is in it, the sanctuary, and its furnishings.”

17The LORD spoke to Moses and to Aaron, saying,

18“Don’t cut off the tribe of the families of the Kohathites from among the Levites;

19but do this to them, that they may live, and not die, when they approach the most holy things: Aaron and his sons shall go in and appoint everyone to his service and to his burden;

20but they shall not go in to see the sanctuary even for a moment, lest they die.”