John Gill Commentary 1 Chronicles 28:13

"also for the courses of the priests and the Levites, and for all the work of the service of the house of Jehovah, and for all the vessels of service in the house of Jehovah;" — 1 Chronicles 28:13 (ASV)

And also for the courses of the priests and Levites
Where they should serve, of which, as fixed and ordered by David, see (1 Chronicles 24:1–26:32)

and for all the work of the service of the house of the Lord ;
they should be employed in:

and for all the vessels of service in the house of the Lord ;
which they should use therein.