1 Chronicles 19:17-19

Modern English Version

¹⁷ When David was told about it, he gathered all Israel, crossed over the Jordan, and came against them. He divided his ranks and prepared to engage the Arameans in battle, so they fought against him. ¹⁸ But the Arameans fled before Israel, and David killed seven thousand chariot drivers and forty thousand infantry men of the Arameans, and killed Shophak, the commander of the army.

¹⁹ And when the servants of Hadadezer saw that they were defeated before Israel, they negotiated peace with David and served him.

So the Arameans were not willing to aid the Ammonites in battle again.