Numbers 4:37-39

American Standard Version

³⁷ These are they that were numbered of the families of the Kohathites, all that did serve in the tent of meeting, whom Moses and Aaron numbered according to the commandment of Jehovah by Moses.

³⁸ And those that were numbered of the sons of Gershon, their families, and by their fathers’ houses, ³⁹ from thirty years old and upward even unto fifty years old, every one that entered upon the service, for work in the tent of meeting,