2 Samuel 13:3-4

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.”