Numbers 4:1-4

Then the Lord spoke to Moses and to Aaron, saying,

“Take a census of the descendants of Kohath from among the sons of Levi, by their families, by their fathers’ households,

from thirty years old and upward, even to fifty years old, everyone who can enter the service of ministry to do work in the tent of meeting.

This is the work of the descendants of Kohath in the tent of meeting, concerning the most holy things.