2 Samuel 13:3-5

3But Amnon had a friend whose name was Jonadab the son of Shimeah, David’s brother. Now Jonadab was a very crafty man.

4And he said to him, “Why are you, the king’s son, becoming thinner day after day? Will you not tell me?” Amnon said to him, “I love Tamar, my brother Absalom’s sister.”

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