Numbers 4:22 BBE

²⁰  But they themselves are not to go in to see the holy place, even for a minute, for fear of death.

²¹  And the Lord said to Moses,

²²  Let the sons of Gershon be numbered by families, in the order of their fathers' houses;

²³  All those from thirty to fifty years old who are able to do the work of the Tent of meeting.

²⁴  This is to be the work of the Gershonites, the things they are to do and take up.