26 Meanwhile, Joab was fighting against Rabbah, the capital of Ammon, and he captured the royal fortifications. 27 Joab sent messengers to tell David, "I have fought against Rabbah and captured its water supply. 28 Now bring the rest of the army and capture the city. Otherwise, I will capture it and get credit for the victory." 29 So David gathered the rest of the army and went to Rabbah, and he fought against it and captured it. 30 David removed the crown from the king's head, and it was placed on his own head. The crown was made of gold and set with gems, and it weighed seventy-five pounds. David took a vast amount of plunder from the city. 31 He also made slaves of the people of Rabbah and forced them to labor with saws, iron picks, and iron axes, and to work in the brick kilns. That is how he dealt with the people of all the Ammonite towns. Then David and all the army returned to Jerusalem.
Matthew Henry's Commentary on 2 Samuel 12:26-31
Commentary on 2 Samuel 12:26-31
(Read 2 Samuel 12:26-31)
To be thus severe in putting the children of Ammon to slavery was a sign that David's heart was not yet made soft by repentance, at the time when this took place. We shall be most compassionate, kind, and forgiving to others, when we most feel our need of the Lord's forgiving love, and taste the sweetness of it in our own souls.