and them that were reckoned by genealogy of the priests by their fathers' houses, and the Levites from twenty years old and upward, in their charges by their courses;
These are they that were numbered of the families of the sons of Merari, whom Moses and Aaron numbered according to the commandment of the LORD by the hand of Moses.
from thirty years old and upward even unto fifty years old, every one that entered in to do the work of service, and the work of bearing burdens in the tent of meeting,