“From thirty years old and upward even unto fifty years old, every one that entereth into the service, for the work in the tabernacle of the congregation:”
Numbers 4:35 (KJV)
Context Reading
33This is the service of the families of the sons of Merari, according to all their service, in the tabernacle of the congregation, under the hand of Ithamar the son of Aaron the priest. 34And Moses and Aaron and the chief of the congregation numbered the sons of the Kohathites after their families, and after the house of their fathers, 35From thirty years old and upward even unto fifty years old, every one that entereth into the service, for the work in the tabernacle of the congregation: 36And those that were numbered of them by their families were two thousand seven hundred and fifty. 37These were they that were numbered of the families of the Kohathites, all that might do service in the tabernacle of the congregation, which Moses and Aaron did number according to the commandment of the LORD by the hand of Moses.