2 Samuel 13:3-5

3But Amnon had a very crafty friend—his cousin Jonadab. He was the son of David’s brother Shimea.

4One day Jonadab said to Amnon, “What’s the trouble? Why should the son of a king look so dejected morning after morning?” So Amnon told him, “I am in love with Tamar, my brother Absalom’s sister.”

5“Well,” Jonadab said, “I’ll tell you what to do. Go back to bed and pretend you are ill. When your father comes to see you, ask him to let Tamar come and prepare some food for you. Tell him you’ll feel better if she prepares it as you watch and feeds you with her own hands.”