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

[107] But when the king of Hamath was informed of the ill success of Hadadezer, and had heard of the ruin of his army, he was afraid on his own account, and resolved to make a league of friendship and fidelity with David before he should come against him; so he sent to him his son Joram, and professed that he owed him thanks for fighting against Hadadezer, who was his enemy, and made a league with him of mutual assistance and friendship. He also sent him presents, vessels of ancient workmanship, both of gold, of silver, and of brass. So when David had made this league of mutual assistance with Toi, (for that was the name of the king of Hamath,) and had received the presents he sent him, he dismissed his son with that respect which was due on both sides; but then David brought those presents that were sent by him, as also the rest of the gold and silver which he had taken of the cities whom he had conquered, and dedicated them to God. Nor did God give victory and success to him only when he went to the battle himself, and led his own army, but he gave victory to Abishai, the brother of Joab, general of his forces, over the Idumeans, ¹ and by him to David, when he sent him with an army into Idumea: for Abishai destroyed eighteen thousand of them in the battle; whereupon the king [of Israel] placed garrisons through all Idumea, and received the tribute of the country, and of every head among them. Now David was in his nature just, and made his determination with regard to truth. He had for the general of his whole army Joab; and he made Jehoshaphat, the son of Ahilud, recorder. He also appointed Zadok, of the family of Phinehas, to be high priest, together with Abiathar, for he was his friend. He also made Seisan the scribe, and committed the command over the guards of his body to Benaiah; the son of Jehoiada. His elder sons were near his body, and had the care of it also.