Numbers 4:41-43

International Standard Version

⁴¹ from the tribes of the descendants of Gershon, everyone who would be serving at the Tent of Meeting, whom Moses and Aaron numbered according to what the Lord had said.

⁴² The tribes and ancestral house of Merari were numbered ⁴³ from 30 to 50 years old; that is, everyone who entered the service to perform work at the Tent of Meeting.