2 Samuel 13:3-5

3However, Amnon had a friend named Jonadab son of Shimeah, David’s brother, and Jonadab was a very shrewd man.

4So he said to him, “Why are you, the king’s son, so miserable morning after morning? Won’t you tell me?” Amnon told him, “I’m in love with Tamar, my brother Absalom’s sister.”

5So Jonadab said to him, “Lie down on your bed and pretend you are sick. When your father comes to see you, say to him, ‘Please let my sister Tamar come and give me some bread to eat. Let her prepare the food in my sight so I may see it and eat from her hand.’”