1 Chronicles 19:5-9

Then there went certain, and told David how the men were served. And he sent to meet them: for the men were greatly ashamed. And the king said, Tarry at Jericho until your beards be grown, and then return.

And when the children of Ammon saw that they had made themselves odious to David, Hanun and the children of Ammon sent a thousand talents of silver to hire them chariots and horsemen out of Mesopotamia, and out of Syria-maachah, and out of Zobah.

So they hired thirty and two thousand chariots, and the king of Maachah and his people; who came and pitched before Medeba. And the children of Ammon gathered themselves together from their cities, and came to battle.

And when David heard of it, he sent Joab, and all the host of the mighty men.

And the children of Ammon came out, and put the battle in array before the gate of the city: and the kings that were come were by themselves in the field.