Numbers 4:15-20

15And when Aaron and his sons have finished covering the sanctuary, and all the vessels of the sanctuary, as the camp is to move forward; after that, the sons of Kohath shall come to bear it : but they shall not touch any holy thing, lest they die. These things are the burden of the sons of Kohath in the tabernacle of the congregation. 16And to the office of Eleazar the son of Aaron the priest pertaineth the oil for the light, and the sweet incense, and the daily meat offering, and the anointing oil, and the oversight of all the tabernacle, and of all that is in it, in the sanctuary, and in its vessels. 17And the LORD spoke to Moses and to Aaron, saying, 18Cut ye not off the tribe of the families of the Kohathites from among the Levites: 19But thus do to them, that they may live, and not die, when they approach to 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 to see when the holy things are covered, lest they die.