2 Samuel 10:19

And when all the kings that were servants to Hadarezer saw that they were smitten before Israel, they made peace with Israel, and served them. So the Syrians feared to help the children of Ammon any more.

Cross-reference

2 Samuel 8:6 describes earlier Syrian subjugation to David, paralleling this later event where vassals submit.

1 Chronicles 19:19 is the parallel account of this same event, with identical wording about the vassals making peace.

1 Kings 20:1 also shows Syrian king Ben-hadad with 32 vassal kings — a later parallel to Hadadezer's coalition.