2 Samuel 10:6
And when the children of Ammon saw that they stank before David, the children of Ammon sent and hired the Syrians of Beth-rehob, and the Syrians of Zoba, twenty thousand footmen, and of king Maacah a thousand men, and of Ish-tob twelve thousand men.
The Ammonites acted after they had scorned and insulted David's ambassadors, knowing they had made themselves odious to David and that the insult would surely be avenged, and therefore they made preparation for war. The hiring of Syrians from Beth-rehob and Zoba, twenty thousand footmen, with a thousand men of king Maacah and twelve thousand men of Ish-tob, formed a vast and formidable coalition of the surrounding nations between the Euphrates and the Mediterranean. That allied force encircled Canaan on the north and east with the purpose of crushing Israel.
The alliance was wholly unprovoked by David, springing not from anything he had done but from jealousy of his increasing power and from hatred of Israel and of the true God. The Ammonites were permitted to carry out the evil purposes of their hearts without restraint, so that their real character might be revealed to David. It was not God's will for Israel to enter into a league with this treacherous heathen people, and their open hostility exposed them as they were.
Out of this coalition grew the greatest wars and victories of David's reign and the most extensive additions to his power.