2 Samuel 13-16 (NIV)
Amnon and Tamar
In the course of time, Amnon son of David fell in love with Tamar, the beautiful sister of Absalom son of David.
2 Amnon became so obsessed with his sister Tamar that he made himself ill. She was a virgin, and it seemed impossible for him to do anything to her.
3 Now Amnon had an adviser named Jonadab son of Shimeah, David’s brother. Jonadab was a very shrewd man. 4 He asked Amnon, “Why do you, the king’s son, look so haggard morning after morning? Won’t you tell me?”
Amnon said to him, “I’m in love with Tamar, my brother Absalom’s sister.”