John Gill Commentary 1 Chronicles 23:2

"And he gathered together all the princes of Israel, with the priests and the Levites." — 1 Chronicles 23:2 (ASV)

And he gathered together all the princes of Israel
Ordered them to be assembled, partly to acquaint them with his will and pleasure, that Solomon should succeed him in the kingdom; and partly to settle the order of the work and service of the temple; and therefore these were convened

with the priests and Levites ;
to assign to them their respective places and offices.