'Kings' in the Bible

When all the kings serving Hadadezer saw that they had been defeated by Israel, they made peace with Israel and served them. So the Arameans (Syrians) were afraid to help the Ammonites anymore.

Then it happened in the spring, at the time when the kings go out to battle, that David sent Joab and his servants with him, and all [the fighting men of] Israel, and they destroyed the Ammonites and besieged Rabbah. But David remained in Jerusalem.