Matthew Poole and continuators on 2 Samuel 12:31

31 And he brought forth the people that were therein , and put them under saws , and under harrows of iron, and under axes of iron , and made them pass through the brick-kiln : and thus did he unto all the cities of the children of Ammon. So David and all the people returned unto Jerusalem.

The words are indefinite, and therefore not necessarily to be understood of all the people; for it had been Barbarous to use Women and Children thus; but of the Men of War, and especially, of those who had been the Chief Actors or Abettors of that Villanous Action against David's Ambassadours, which was contrary to the Law of Nature, and of Nations, and of all Humanity, and of the Dreadful War ensuing upon it; for which, they might seem to deserve, the severest Punishments. Although indeed there seems to have been too much Rigour used; especially, because these dreadful Deaths were Inflicted not onely upon those great Counsellors, who were the onely Authors of that vile Usage of the Ambassadours; but upon a great number of the People who were Innocent from that Crime. And therefore it is probably conceived, That David exercised this Cruelty whilst his Heart was hardned, and impenitent; and when he was bereaved of that free and good Spirit of God, which would have taught him more Mercy and Moderation.

He Sawed them to Death: of which Punishment, we have Examples both in Scripture, Heb. 11. 37. and in other Authors.

He caused them to be laid down upon the Ground, and [illegible: 1+ letters]orn by sharp Iron Harrows drawn over them, and hewed in pieces by keen Axes.

i. e. To be burnt in Brick-kilns. Or, made them to pass through the furnace of Malchen: i. e. of Moloch, called also Milchom, and here Malchen; Punishing them with their own Sin, and with the same kind of Punishment which they Inflicted upon their own Children: See 2 King. 16. 3. and 23. 10. and Levit. 18. 21. and 20. 2. and Deut. 18. 10.