I Chronicles 23:6

And David divided them into courses among the sons of Levi,.... Into three classes, according to the number of them, which follow: namely: Gershon, Kohath, and Merari; see Exo 6:16.

David, having given charge concerning the building of the temple, in this and the following chapters settles the method of the temple-service and puts into order the offices and officers of it. In the late irregular times, and during the wars in the beginning of his reign, we may suppose that, though the Levitical ordinances were kept up, yet it was not in the order, nor with the beauty and exactness, that were desirable. Now David, being a prophet, as well as a prince, by divine warrant and direction, "set in order the things that were wanting." In this chapter we are informed, I. He declared Solomon to be his successor, (Ch1 23:1). II. He numbered the Levites, and appointed them to their respective offices (Ch1 23:2-5). III. He took an account of the several families of the Levites (v. 6-23). IV. He made a new reckoning of them from twenty years old, and appointed them their work (Ch1 23:24-32). And in this he prepared for the temple as truly as when he laid up gold and silver for it; for the place is of small account in comparison with the work.

23:6-23 David divided the Levites into divisions according to their ancestral families. The number of available clerics far exceeded the requirements for a single Temple; the divisions provided a necessary time-sharing mechanism that enabled all the priests and Levites to serve in the Temple periodically (cp. Luke 1:5, 8).