Numbers 4:23-25

Amplified Bible

²³ From thirty years and upward to fifty years old, you shall number them; all who enter for 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 carrying [when on the march]: ²⁵ they shall carry the tent curtains of the tabernacle, and the Tent of Meeting, its covering and the covering of porpoise skin (fine leather) that is on top of it, and the curtain for the doorway of the Tent of Meeting (tabernacle),