32 Then Jonadab the son of Shimeah, David's brother, answered and said, "Let not my lord suppose they have killed all the young men, the king's sons, for only Amnon is dead. For by the command of Absalom this has been determined from the day that he forced his sister Tamar.
Matthew Henry's Commentary on 2 Samuel 13:32
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.