TSK · Numbers 10:21

When the tabernacle is to move, the Levites shall take it down; and when the tabernacle is to be set up, the Levites shall set it up. The stranger who comes near shall be put to death.

Of Kohath was the family of the Amramites, and the family of the Izharites, and the family of the Hebronites, and the family of the Uzzielites: these are the families of the Kohathites.

"When Aaron and his sons have finished covering the sanctuary, and all the furniture of the sanctuary, as the camp moves forward; after that, the sons of Kohath shall come to carry it: but they shall not touch the sanctuary, lest they die. These things are the burden of the sons of Kohath in the Tent of Meeting.

But to the sons of Kohath he gave none, because the service of the sanctuary belonged to them; they carried it on their shoulders.

Then David said, "No one ought to carry the ark of God but the Levites. For Yahweh has chosen them to carry the ark of God, and to minister to him forever."