Numbers 4:20-25
English Standard Version
21The Lord spoke to Moses, saying,
22"Take a census of the sons of Gershon also, by their fathers ' houses and by their clans.
23From thirty years old up to fifty years old, you shall list them, all who can come to do duty, to do service in the tent of meeting.
24This is the service of the clans of the Gershonites, in serving and bearing burdens:
25they 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