1 Chronicles 23:24

These were the sons of Levi, after the house of their fathers,
&c.] According to the three classes of them, as descending from the three sons of Levi:

[even] the chief of the fathers;
or heads of families:

as they were counted by number of names by their polls;
or according to their heads, one by one:

that did the work for the service of the house of the Lord;
the particulars of which are in ( 1 Chronicles 23:28-31 )

from the age of twenty years, and upwards;
they were first numbered thirty and upwards, ( 1 Chronicles 23:3 ) , but David before his death ordered they should be numbered from twenty and upwards, ( 1 Chronicles 23:27 ) , because the Israelites being increased, there would be more work for the priests in the temple, which would require the assistance of more Levites. The reasons follow.