3 But Amnon had a friend, whose name was Jon'adab, the son of Shim'e-ah, David's brother; and Jon'adab was a very crafty man. 4 And he said to him, "O son of the king, why are you so haggard morning after morning? Will you not tell me?" Amnon said to him, "I love Tamar, my brother Ab'salom's sister." 5 Jon'adab said to him, "Lie down on your bed, and pretend to be ill; and when your father comes to see you, say to him, 'Let my sister Tamar come and give me bread to eat, and prepare the food in my sight, that I may see it, and eat it from her hand.'" 6 So Amnon lay down, and pretended to be ill; and when the king came to see him, Amnon said to the king, "Pray let my sister Tamar come and make a couple of cakes in my sight, that I may eat from her hand."
Matthew Henry's Commentary on 2 Samuel 13:3-6
Commentary on 2 Samuel 13:1-20
(Read 2 Samuel 13:1-20)
From henceforward David was followed with one trouble after another. Adultery and murder were David's sins, the like sins among his children were the beginnings of his punishment: he was too indulgent to his children. Thus David might trace the sins of his children to his own misconduct, which must have made the anguish of the chastisement worse. Let no one ever expect good treatment from those who are capable of attempting their seduction; but it is better to suffer the greatest wrong than to commit the least sin.