Numbers 3:22-26

Their numbered men, in the counting of every male from a month old and upward, their numbered men were 7,500.

The families of the Gershonites were to camp behind the tabernacle westward,

and the leader of the fathers’ households of the Gershonites: Eliasaph the son of Lael. Duties of the Levites

Now the duties of the sons of Gershon in the tent of meeting included the tabernacle and the tent, its covering, and the curtain for the entrance of the tent of meeting,

and the curtains of the courtyard, the curtain for the entrance of the courtyard which is around the tabernacle and the altar, and its ropes, according to all the service concerning them.