Numbers 4:21 – 37
The Lord spoke to Moses: Take a census of the Gershonites also, by their ancestral house and by their clans. Record them from the age of thirty years up to the age of fifty, all who are subject to service in the performance of tasks for the Tent of Meeting. These are the duties of the Gershonite clans as to labor and porterage: they shall carry the cloths of the Tabernacle, the Tent of Meeting with its covering, the covering of dolphin skin that is on top of it, and the screen for the entrance of the Tent of Meeting; the hangings of the enclosure, the screen at the entrance of the gate of the enclosure that surrounds the Tabernacle, the cords thereof, and the altar, and all their service equipment and all their accessories; and they shall perform the service. All the duties of the Gershonites, all their porterage and all their service, shall be performed on orders from Aaron and his sons; you shall make them responsible for attending to all their porterage. Those are the duties of the Gershonite clans for the Tent of Meeting; they shall attend to them under the direction of Ithamar son of Aaron the priest.
As for the Merarites, you shall record them by the clans of their ancestral house; you shall record them from the age of thirty years up to the age of fifty, all who are subject to service in the performance of the duties for the Tent of Meeting. These are their porterage tasks in connection with their various duties for the Tent of Meeting: the planks, the bars, the posts, and the sockets of the Tabernacle; the posts around the enclosure and their sockets, pegs, and cords--all these furnishings and their service: you shall list by name the objects that are their porterage tasks. Those are the duties of the Merarite clans, pertaining to their various duties in the Tent of Meeting under the direction of Ithamar son of Aaron the priest. So Moses, Aaron, and the chieftains of the community recorded the Kohathites by the clans of their ancestral house, from the age of thirty years up to the age of fifty, all who were subject to service for work relating to the Tent of Meeting. Those recorded by their clans came to 2,750. That was the enrollment of the Kohathite clans, all those who performed duties relating to the Tent of Meeting, whom Moses and Aaron recorded at the command of the Lord through Moses.