And when Aaron and his sons have made an end of covering the sanctuary, and all the vessels of the sanctuary, as the camp is to set 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. (Numbers 4:15)
No Levite was allowed to touch the holy things until they had been covered and packed by Aaron and his priests; the Kohathites would then simply lift up the bundles and transport them (vs. 12-14).