2 Samuel 13:3-5

3But Amnon had a friend whose name was Jonadab, the son of 12Shimeah, David’s brother; and Jonadab was a very shrewd man.

4He said to him, “O son of the king, why are you so depressed morning after morning? Will you not tell me?” Then Amnon said to him, “I am in love with Tamar, the sister of my brother Absalom.”

5Jonadab then said to him, “Lie down on your bed and pretend to be ill; when your father comes to see you, say to him, ‘Please let my sister Tamar come and give me some food to eat, and let her prepare the food in my sight, that I may see it and eat from her hand.’”