KJV:
And when the servants of Hadarezer saw that they were put to the worse before Israel, they made peace with David, and became his servants: neither would the Syrians help the children of Ammon any more.
NASB:
So when the servants of Hadadezer saw that they were defeated by Israel, they made peace with David and served him. Thus the Arameans were not willing to help the sons of Ammon anymore.