Numbers 4:16-20

16“The appointed responsibility of Eleazar son of Aaron the priest is for the oil for the light, and the spiced incense, and the daily grain offering, and the anointing oil; he also has the appointed responsibility over all the tabernacle with all that is in it, over the sanctuary and over all its furnishings.”

17Then the Lord spoke to Moses and Aaron:

18“Do not allow the tribe of the families of the Kohathites to be cut off from among the Levites;

19but in order that they will live and not die when they approach the most holy things, do this for them: Aaron and his sons will go in and appoint each man to his service and his responsibility.

20But the Kohathites are not to go in to watch while the holy things are being covered, or they will die.”