1 Chronicles 20:3
And he brought out the people that were in it, and cut them with saws, and with harrows of iron, and with axes. Even so dealt David with all the cities of the children of Ammon. And David and all the people returned to Jerusalem. And he brought out the people that were in it, and cut them with saws, and with harrows of iron, and with axes. Even so dealt David with all the cities of the children of Ammon. And David and all the people returned to Jerusalem.
The verse does not describe torturing or killing the people of Rabbah with saws, iron harrows, and axes, but bringing them out of the city and putting them to work with those tools. It may be rendered as making the people laborers in iron works, set to sawing and working with iron tools. It can be rendered as saying that David put the Ammonites to work with saws, iron harrows, axes, and brick-kilns, rather than that he cut them with them.
The Hebrew word rendered harrows of iron may also mean iron mines. Seven Hebrew manuscripts support reading he put them to saws. This means he employed them as slaves in hard, low-status labor or service, and the verse thus records the subjection of the conquered Ammonite cities to labor after their conquest.
The captives passed before David at a paved area, where he assigned them to the kinds of work they were suited for, and they became foreign laborers and workmen. By this labor David taught the Ammonites mechanical and agricultural arts, including work at brick-kilns, and made them a peaceful, useful people. The verse therefore shows that David was not cruel to his enemies.