All the service of the Gershonites--all their transport duties and other work--is to be done at the direction of Aaron and his sons; you are to assign to them all that they are responsible to carry.

Numbers 4:26
the curtains of the courtyard, and the curtains for the entrance at the gate of the courtyard that surrounds the tabernacle and altar, along with their ropes and all the equipment for their service. The Gershonites will do all that needs to be done with these items.

Numbers 4:28
This is the service of the Gershonite clans at the Tent of Meeting, and their duties shall be under the direction of Ithamar son of Aaron the priest.

At the appointment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burdens, and in all their service: and you shall appoint to them in charge all their burdens.