Numbers 4:22-28

22“Take a census of the sons of Gershon also, by their fathers’ households, by their families.

23From thirty years and upward to fifty years old, you shall number them; all who enter for service to do the work in the Tent of Meeting.

24This is the service of the families of the Gershonites, in serving and in carrying [when on the march]:

25they shall carry the tent curtains of the tabernacle, and the Tent of Meeting, its covering and the covering of porpoise skin (fine leather) that is on top of it, and the curtain for the doorway of the Tent of Meeting (tabernacle),

26and the hangings of the courtyard, and the curtain for the entrance of the gate of the courtyard which is around the tabernacle and the altar, and their tent ropes, and all the equipment for their service; and all that is to be done, they shall perform.

27Aaron and his sons shall direct all the service of the sons of the Gershonites, all they have to carry and all they have to do. You shall assign to them as a duty all that they are to carry [on the march].

28This is the service of the families of the sons of Gershon in the Tent of Meeting (tabernacle); and their duties shall be under the direction of Ithamar the son of Aaron, the [high] priest.