Charles Ellicott Commentary 1 Kings 12:17

"But as for the children of Israel that dwelt in the cities of Judah, Rehoboam reigned over them." — 1 Kings 12:17 (ASV)

The children of Israel who dwelt in the cities of Judah. —The expression is doubly significant. (a) Historically, the tribe of Judah had its semi-dependent tribes—Simeon, already absorbed into Judah; Dan, largely transferred to the extreme north; and Benjamin, closely united to Judah by the position of Jerusalem. All these, it would seem, are here included—so that the territory of the southern kingdom would be really the Judæa of later times.

In addition to these, we find from 2 Chronicles 11:13–16, that, at least after the idolatry of Jeroboam, priests and Levites and other Israelites made their way into the cities of Judah. (b) But, besides this, there may be a significance in the phrase “children of Israel.” Although the northern kingdom from then on inherited the proud title of the kingdom of Israel, the phrase, as here used, is perhaps intended to remind the reader that in Judah also dwelt “children of Israel”—true descendants of the “Prince of God,” and inheritors of the promise.