Numbers 4:4-5

4:4 This is the service of the Kohathites in the tent of meeting, relating to the most holy things. 4:5 When it is time for the camp to journey, Aaron and his sons must come and take down the screening curtain and cover the ark of the testimony with it.

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 4:20

4:20 But the Kohathites are not to go in to watch while the holy things are being covered, or they will die.”