Numbers 4:27-29

King James Version

²⁷ At the appointment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burdens, and in all their service: and ye shall appoint unto them in charge all their burdens.

²⁸ This is the service of the families of the sons of Gershon in the tabernacle of the congregation: and their charge shall be under the hand of Ithamar the son of Aaron the priest.

²⁹ As for the sons of Merari, thou shalt number them after their families, by the house of their fathers;