Numbers 4:29-31

King James Version

²⁹ As for the sons of Merari, thou shalt number them after their families, by the house of their fathers;

³⁰ From thirty years old and upward even unto fifty years old shalt thou number them, every one that entereth into the service, to do the work of the tabernacle of the congregation.

³¹ And this is the charge of their burden, according to all their service in the tabernacle of the congregation; the boards of the tabernacle, and the bars thereof, and the pillars thereof, and sockets thereof,