Matthew Poole and continuators on 1 Chronicles 27:1

1 NOw the children of Israel after their number, to wit, the chief fathers and captains of thousands and hundreds, and their officers that served the king in any matter of the courses , which came in and went out month by month , throughout all the months of the year, of every course were twenty and four thousand.

The standing Force or Militia of Israel as it was settled under their several Officers, as it here follows.

i. e. In all the business wherein the King had occasion for these Persons who were to attend upon him or his Commands by Courses or by Turns. Or, according to all the order or state of the Divisions, or, about the Companies or Courses into which they were distributed.

i. e. Executed their Office: which is commonly signified by this Phrase, as Numb. 27. 17. and elsewhere.

Who were to be Armed and Mustered and to wait upon the King either at Jerusalem on in other places as the King should see fit. By this Order near 300000 of his People were instructed and exercised in the use of the Arms and fitted for the Defence of their King and Kingdom when it should be needful, and in the mean time sufficient Provision was made against any sudden Tumults or Irruptions of Enemies. And this monthly Course was contrived that the Burden of it might be easie and equally distributed [illegible: 1 word] the People.