Numbers 4:37-39

International Standard Version

³⁷ from the tribe of the descendants of Kohath, everyone who would be serving at the Tent of Meeting, whom Moses and Aaron numbered according to what the Lord had said, under the supervision of Moses.

³⁸ The tribes and the ancestral houses of the descendants of Gershon were numbered ³⁹ from 30 to 50 years old; that is, everyone who entered the service to perform work at the Tent of Meeting.