2 Samuel 13:1-4

Some time later, this happened: Absalom, David’s son, had a sister who was very attractive. Her name was Tamar. Amnon, also David’s son, was in love with her. Amnon was obsessed with his sister Tamar to the point of making himself sick over her. She was a virgin, so he couldn’t see how he could get his hands on her. Amnon had a good friend, Jonadab, the son of David’s brother Shimeah. Jonadab was exceptionally streetwise. He said to Amnon, “Why are you moping around like this, day after day—you, the son of the king! Tell me what’s eating at you.” “In a word, Tamar,” said Amnon. “My brother Absalom’s sister. I’m in love with her.”