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

[186] Now, in the second year of the reign of Joash over Israel, Amaziah reigned over the tribe of Judah in Jerusalem. His mother's name was Jehoaddan, who was born at Jerusalem. He was exceeding careful of doing what was right, and this when he was very young; but when he came to the management of affairs, and to the government, he resolved that he ought first of all to avenge his father Je-hoash, and to punish those his friends that had laid violent hands upon him: so he seized upon them all, and put them to death; yet did he execute no severity on their children, but acted therein according to the laws of Moses, who did not think it just to punish children for the sins of their fathers. After this he chose him an army out of the tribe of Judah and Benjamin, of such as were in the flower of their age, and about twenty years old; and when he had collected about three hundred thousand of them together, he set captains of hundreds over them. He also sent to the king of Israel, and hired a hundred thousand of his soldiers for a hundred talents of silver, for he had resolved to make an expedition against the nations of the Amatekites, and Edomites, and Gebalites: but as he was preparing for his expedition, and ready to go out to the war, a prophet gave him counsel to dismiss the army of the Israelites, because they were bad men, and because God foretold that he should be beaten, if he made use of them as auxiliaries; but that he should overcome his enemies, though he had but a few soldiers, when it so pleased God. And when the king grudged at his having already paid the hire of the Israelites, the prophet exhorted him to do what God would have him, because he should thereby obtain much wealth from God. So he dismissed them, and said that he still freely gave them their pay, and went himself with his own army, and made war with the nations before mentioned; and when he had beaten them in battle, he slew of them ten thousand, and took as many prisoners alive, whom he brought to the great rock which is in Arabia, and threw them down from it headlong. He also brought away a great deal of prey and vast riches from those nations. But while Amaziah was engaged in this expedition, those Israelites whom he had hired, and then dismissed, were very uneasy at it, and taking their dismission for an affront, (as supposing that this would not have been done to them but out of contempt,) they fell upon his kingdom, and proceeded to spoil the country as far as Beth-horon, and took much cattle, and slew three thousand men.