Numbers 4:21-28 - Duties Of The Gershonites
21 And the LORD spake unto Moses, saying, 22 "Take the sum of the children of Gershon, in the houses of their fathers and in their kindreds - 23 from thirty years and above, until fifty, all that are able to go forth in war - for to do service in the tabernacle of witness. 24 And this is the service of the kindred of the Gershonites, to serve and to bear. 25 They shall bear the curtains of the dwelling and the roof of the tabernacle of witness and his covering and the covering of taxus' skins that is on high above upon it, and the hanging of the door of the tabernacle of witness: 26 and the hanging of the court and the hanging of the gate of the court that is round about the dwelling and the altar, and the cords of them, and all the instruments that serve unto them and all that is made for them.
27 And at the mouth of Aaron and his sons, shall all the service of the children of the Gershonites be done, in all their charges and in all their service, and ye shall appoint them unto all their charges that they shall wait upon. 28 And this is the service of the kindred of the children of the Gershonites in the tabernacle of witness, and their wait shall be in the hand of Ithamar the son of Aaron the priest.