Numbers 4:3 in the King James Version
From thirty years old and upward even until fifty years old, all that enter into the host, to do the work in the tabernacle of the congregation.
Context
2 “Take a census of the sons of Kohath from among the sons of Levi, by their families, by their fathers’ houses,
3 from thirty years old and upward even until fifty years old, all who enter into the service to do the work in the Tent of Meeting.
4 “This is the service of the sons of Kohath in the Tent of Meeting, regarding the most holy things.