Numbers 4:23
from thirty to fifty years old, counting everyone who comes to serve in the work at the Tent of Meeting.
Berean Standard Bible
From thirty years old and upward until fifty years old shalt thou number them; all that enter in to perform the service, to do the work in the tabernacle of the congregation.
you shall count them from thirty years old and upward until fifty years old: all who enter in to wait on the service, to do the work in the Tent of Meeting.