Numbers 4:20-24

but they shall not come in to see the holy objects even for a moment, or they will die.” Duties of the Gershonites

Then the Lord spoke to Moses, saying,

“Take a census of the sons of Gershon also, by their fathers’ households, by their families;

from thirty years old and upward to fifty years old you shall count them: all who can enter to perform service, to do the work in the tent of meeting.

This is the service of the families of the Gershonites, in serving and in carrying: