Numbers 4:5-6, 15

When the camp is to move, Aaron and his sons are to go in and take down the shielding curtain and put it over the ark of the covenant law. Then they are to cover the curtain with a durable leather, spread a cloth of solid blue over that and put the poles in place.

“After Aaron and his sons have finished covering the holy furnishings and all the holy articles, and when the camp is ready to move, only then are the Kohathites to come and do the carrying. But they must not touch the holy things or they will die. The Kohathites are to carry those things that are in the tent of meeting.