both to the genealogy of the priests by the house of their fathers, 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 Gershon, of all that might do service in the tabernacle of the congregation, whom Moses and Aaron did number according to the commandment of the Lord.
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,