Numbers 4:25; Numbers 4:28

25 they shall carry the curtains of the tabernacle and the tent of meeting with its covering and the covering of goatskin that is on top of it and the screen for the entrance of the tent of meeting

28 This is the service of the clans of the sons of the Gershonites in the tent of meeting, and their guard duty is to be under the direction of Ithamar the son of Aaron the priest.