1 Chronicles 19:7-11

So they hired for themselves thirty-two thousand chariots, and the king of Maacah and his people, who came and camped opposite Medeba. And the sons of Ammon gathered together from their cities and came to the battle.

When David heard about it, he sent Joab and all the army, the mighty men.

The sons of Ammon came out and drew up in battle formation at the entrance of the city; and the kings who had come were by themselves in the field. Ammon and Aram Defeated

Now when Joab saw that the battle was set against him at the front and at the rear, he selected warriors from all the choice men in Israel and lined them up against the Arameans.

But the remainder of the people he placed under the command of Abshai his brother; and they lined up against the sons of Ammon.