Numbers 4:15

4:15 “When Aaron and his sons have finished covering the sanctuary and all the furnishings of the sanctuary, when the camp is ready to journey, then the Kohathites will come to carry them; but they must not touch any holy thing, or they will die. These are the responsibilities of the Kohathites with the tent of meeting.

Numbers 4:19

4:19 but 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.