Numbers 4:21-28 - Duties Of The Gershonites
21 Yahweh spoke to Moses, saying, 22 "Take a census of the sons of Gershon also, by their fathers' houses, by their families; 23 you shall count them from thirty years old and upward until fifty years old; all who enter in to wait on the service, to do the work in the Tent of Meeting. 24 "This is the service of the families of the Gershonites, in serving and in bearing burdens: 25 they shall carry the curtains of the tabernacle, and the Tent of Meeting, its covering, and the covering of sealskin that is above on it, and the screen for the door of the Tent of Meeting, 26 and the hangings of the court, and the screen for the door of the gate of the court, which is by the tabernacle and around the altar, and their cords, and all the instruments of their service, and whatever shall be done with them. Therein shall they serve.
27 At the commandment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burden, and in all their service; and you shall appoint their duty to them in all their responsibilities. 28 This is the service of the families of the sons of the Gershonites in the Tent of Meeting: and their duty shall be under the hand of Ithamar the son of Aaron the priest.