Numbers 4:19 (KJV)

And they shall put upon it all the vessels thereof, wherewith they minister about it, even the censers, the fleshhooks, and the shovels, and the basons, all the vessels of the altar; and they shall spread upon it a covering of badgers' skins, and put to the staves of it.

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.

And to the office of Eleazar the son of Aaron the priest pertaineth the oil for the light, and the sweet incense, and the daily meat offering, and the anointing oil, and the oversight of all the tabernacle, and of all that therein is, in the sanctuary, and in the vessels thereof.

And the LORD spake unto Moses and unto Aaron saying,

Cut ye not off the tribe of the families of the Kohathites from among the Levites:

But they shall not go in to see when the holy things are covered, lest they die.

And the LORD spake unto Moses, saying,

Take also the sum of the sons of Gershon, throughout the houses of their fathers, by their families;

From thirty years old and upward until fifty years old shalt thou number them; all that enter in to perform the service, to do the work in the tabernacle of the congregation.

This is the service of the families of the Gershonites, to serve, and for burdens: