Jamieson, Fausset and Brown on 1 Chronicles 20:3

3. cut them with saws, &c.--The Hebrew word, "cut them," is, with the difference of the final letter, the same as that rendered "put them," in the parallel passage of Samuel [2Sa 12:31]; and many consider that putting them to saws, axes, and so forth, means nothing more than that David condemned the inhabitants of Rabbah to hard and penal servitude.

1Ch 20:4-8. Three Overthrows of the Philistines and Three Giants Slain.