2 Samuel 13:1-4

Now David’s son Absalom had a beautiful sister named Tamar. And Amnon, her half brother, fell desperately in love with her. Amnon became so obsessed with Tamar that he became ill. She was a virgin, and Amnon thought he could never have her. But Amnon had a very crafty friend—his cousin Jonadab. He was the son of David’s brother Shimea. One 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.”