John Gill's Exposition of the Whole Bible
1 Kings 2:32
And the Lord shall return his blood upon his own head,.... By way of retaliation, blood for blood:
who fell upon two men more righteous and better than he; later named; for though they had been in open rebellion against David, yet had submitted, and were reconciled and received into favour; and even their open crimes were not so bad, Solomon judged, as his secret treacherous murders of innocent persons in cool blood; they were men of more honour and integrity than he was, not so cruel and barbarous, though guilty in other respects:
and slew them with the sword, my father not knowing [thereof]; this is observed to remove all suspicion, and which doubtless had been entertained by some, that David had an hand in their death; and that Joab did what he did with his knowledge and consent, and by his advice and order; they having been both concerned in rebellion against him, the one under Ishbosheth, and the other under Absalom:
[to wit], Abner the son of Ner, captain of the host of Israel, and Amasa the son of Jether, captain of the host of Judah: the reason of the two hosts, of which they were captains or generals, being thus distinguished, is, because the tribes of Israel were on the side of Ishbosheth, whose general Abner was, in opposition to Judah, who made David their king; and, on the other hand, they were the men of Judah that were first and chiefly in the rebellion of Absalom, whose general Amasa was; of the murder of these two men by Joab, see 2 Samuel 3:27.