Albert Barnes Commentary 2 Chronicles 23:2

"And they went about in Judah, and gathered the Levites out of all the cities of Judah, and the heads of fathers` [houses] of Israel, and they came to Jerusalem." — 2 Chronicles 23:2 (ASV)

Jehoiada was unwilling to trust the success of the revolution wholly and entirely to the royal bodyguard. Accordingly, the captains gathered from the cities of Judah a strong body of Levites and the heads of the families of Israel (that is, “Judah,” see the note on 2 Chronicles 20:34), who were brought to Jerusalem.