Charles Ellicott Commentary 2 Chronicles 23:8

"So the Levites and all Judah did according to all that Jehoiada the priest commanded: and they took every man his men, those that were to come in on the sabbath; with those that were to go out on the sabbath; for Jehoiada the priest dismissed not the courses." — 2 Chronicles 23:8 (ASV)

The Levites and all Judah. — 2 Kings 11:9 reads, the captains of the hundreds. The rest of the verse is the same in both narratives as far as the words go out on the Sabbath.

For Jehoiada the priest dismissed not the courses. — The companies of priests and Levites, whose weekly duties had been fulfilled, and who under ordinary circumstances would have been formally “dismissed” by the high priest, were detained at the present emergency as auxiliaries to their brothers who were “coming in.”

Instead of this clause, Kings has: And they came to Jehoiada the priest, that is, the captains of the hundreds came to him; a remark which quite naturally preludes the statement of the next verse both there and here.