2 Samuel 12:31 - Matthew Poole's English Annotations on the Holy Bible

The people that were therein: 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 villainous action against David's ambassadors, (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 only upon those great counsellors, who were the only authors of that vile usage of the ambassadors; 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 hardened and impenitent, and when he was bereaved of that free and good Spirit of God which would have taught him more mercy and moderation. Put them under saws: he sawed them to death; of which punishment we have examples, both in Scripture, Hebrews 11:37, and in other authors. Under harrows of iron, and under axes of iron; he caused them to be laid down upon the ground, and torn by sharp iron harrows drawn over them, and hewed in pieces by keen axes. Made them pass through the brick-kiln, i.e. to be burnt in brickkilns. 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 Kings 16:3, 2 Kings 23:10 Leviticus 18:21, Leviticus 20:2 Deuteronomy 18:10.