I Chronicles 20:1-3

It happened in the spring of the year, at the time kings go out to battle, that Joab led out the armed forces and ravaged the country of the people of Ammon, and came and besieged Rabbah. But David stayed at Jerusalem. And Joab defeated Rabbah and overthrew it. Then David took their king’s crown from his head, and found it to weigh a talent of gold, and there were precious stones in it. And it was set on David’s head. Also he brought out the spoil of the city in great abundance. And he brought out the people who were in it, and put them to work with saws, with iron picks, and with axes. So David did to all the cities of the people of Ammon. Then David and all the people returned to Jerusalem.