These were the sons of Levi after the house of their fathers; even the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.
These were the sons of Levi ... that did the work ... from ... twenty years and upward. The enumeration of the Levites was made by David (1 Chronicles 23:3) on the same rule as that followed by Moses (Numbers 4:3) - namely, from thirty years. But he saw afterward that this rule might be beneficially relaxed, and that the enrollment of Levites for their proper duties might be made from 20 years of age. The ark and tabernacle being now stationary at Jerusalem, the labour of the Levites was greatly diminished, as they were no longer obliged to transport its heavy furniture from place to place.