Numbers 4:16-20

16And Eleazar the son of Aaron the priest shall have the oversight of the oil for the light, and the fragrant incense, and the continual oblation, and the anointing oil, — the oversight of the whole tabernacle, and of all that is therein, over the sanctuary, and over its furniture.

17And Jehovah spoke to Moses and to Aaron, saying,

18Ye shall not cut off the families of the Kohathites from among the Levites,

19but this shall ye do unto them, that they may live, and not die, when they draw near unto the most holy things: Aaron and his sons shall go in, and appoint them every one to his service and to his burden;

20but they shall not go in and see for a moment the holy things, lest they die.