2 Samuel 13:1-4

Now Absalom, David’s son, had a beautiful sister, whose name was Tamar. And after a time Amnon, David’s son, loved her. And Amnon was so tormented that he made himself ill because of his sister Tamar, for she was a virgin, and it seemed impossible to Amnon to do anything to her. But Amnon had a friend, whose name was Jonadab, the son of Shimeah, David’s brother. And Jonadab was a very crafty man. And he said to him, “O son of the king, why are you so haggard morning after morning? Will you not tell me?” Amnon said to him, “I love Tamar, my brother Absalom’s sister.”