Numbers 4:3-5

Darby Translation

³ from thirty years old and upward even unto fifty years old, all that enter into the service, to do the work in the tent of meeting.

⁴ This shall be the service of the sons of Kohath in the tent of meeting: it is most holy.

⁵ And when the camp setteth forward, Aaron and his sons shall go in, and they shall take down the veil of separation and cover the ark of testimony with it;