28 Then Absalom commanded his servants, "Watch when Amnon's heart is merry with wine, and when I say to you, "Strike Amnon,' then kill him. Do not be afraid; have I not myself commanded you? Be courageous and valiant." 29 So the servants of Absalom did to Amnon as Absalom had commanded. Then all the king's sons rose, and each mounted his mule and fled.
30 While they were on the way, the report came to David that Absalom had killed all the king's sons, and not one of them was left. 31 The king rose, tore his garments, and lay on the ground; and all his servants who were standing by tore their garments. 32 But Jonadab, the son of David's brother Shimeah, said, "Let not my lord suppose that they have killed all the young men the king's sons; Amnon alone is dead. This has been determined by Absalom from the day Amnon raped his sister Tamar. 33 Now therefore, do not let my lord the king take it to heart, as if all the king's sons were dead; for Amnon alone is dead." 34 But Absalom fled. When the young man who kept watch looked up, he saw many people coming from the Horonaim road by the side of the mountain. 35 Jonadab said to the king, "See, the king's sons have come; as your servant said, so it has come about." 36 As soon as he had finished speaking, the king's sons arrived, and raised their voices and wept; and the king and all his servants also wept very bitterly. 37 But Absalom fled, and went to Talmai son of Ammihud, king of Geshur. David mourned for his son day after day. 38 Absalom, having fled to Geshur, stayed there three years.
Matthew Henry's Commentary on 2 Samuel 13:28-38
Commentary on 2 Samuel 13:21-29
(Read 2 Samuel 13:21-29)
Observe the aggravations of Absalom's sin: he would have Ammon slain, when least fit to go out of the world. He engaged his servants in the guilt. Those servants are ill-taught who obey wicked masters, against God's commands. Indulged children always prove crosses to godly parents, whose foolish love leads them to neglect their duty to God.
Commentary on 2 Samuel 13:30-39
(Read 2 Samuel 13:30-39)
Jonadab was as guilty of Ammon's death, as of his sin; such false friends do they prove, who counsel us to do wickedly. Instead of loathing Absalom as a murderer, David, after a time, longed to go forth to him. This was David's infirmity: God saw something in his heart that made a difference, else we should have thought that he, as much as Eli, honoured his sons more than God.