Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[127] This defeat did not still induce the Ammonites to be quiet, nor to own those that were superior to them to be so, and be still, but they sent to Chalaman, the king of the Syrians, beyond Euphrates, and hired him for an auxiliary. He had Shobach for the captain of his host, with eighty thousand footmen, and ten thousand horsemen. Now when the king of the Hebrews understood that the Ammonites had again gathered so great an army together, he determined to make war with them no longer by his generals, but he passed over the river Jordan himself with all his army; and when he met them he joined battle with them, and overcame them, and slew forty thousand of their footmen, and seven thousand of their horsemen. He also wounded Shobach, the general of Chalaman's forces, who died of that stroke; but the people of Mesopotamia, upon such a conclusion of the battle, delivered themselves up to David, and sent him presents, who at winter time returned to Jerusalem. But at the beginning of the spring he sent Joab, the captain of his host, to fight against the Ammonites, who overran all their country, and laid it waste, and shut them up in their metropolis Rabbah, and besieged them therein.