II Samuel 13:2, 4

Amnon was so distressed over his sister Tamar that he became sick; for she was a virgin. And it was improper for Amnon to do anything to her.

And he said to him, “Why are you, the king’s son, becoming thinner day after day? Will you not tell me?” Amnon said to him, “I love Tamar, my brother Absalom’s sister.”