1 Chronicles 20:1-3

Then it happened in the spring, at the time when kings go out to battle, that Joab led out the army and ravaged the land of the sons of Ammon, and came and besieged Rabbah. But David stayed at Jerusalem. And Joab struck Rabbah and overthrew it. David took the crown of their king from his head, and he found it to weigh a talent of gold, and there was a precious stone in it; and it was placed on David’s head. And he brought out the spoil of the city, a very great amount. He brought out the people who were in it, and cut them with saws and with sharp instruments and with axes. And thus David did to all the cities of the sons of Ammon. Then David and all the people returned to Jerusalem.