Absalom son of David had a fair sister whose name was Tamar, and Amnon [her half brother] son of David loved her. And Amnon was so troubled that he fell sick for his [half] sister Tamar, for she was a virgin, and Amnon thought it impossible for him to do anything to her. But Amnon had a friend whose name was Jonadab son of Shimeah, David's brother; and Jonadab was a very crafty man. read more.
He said to Amnon, Why are you, the king's son, so lean and weak-looking from day to day? Will you not tell me? And Amnon said to him, I love Tamar, my [half] brother Absalom's sister. Jonadab said to him, Go to bed and pretend you are sick; and when your father David comes to see you, say to him, Let my sister Tamar come and give me food and prepare it in my sight, that I may see it and eat it from her hand. So Amnon lay down and pretended to be sick; and when the king came to see him, Amnon said to the king, I pray you, let my sister Tamar come and make me a couple of cakes in my sight, that I may eat from her hand. Then David sent home and told Tamar, Go now to your brother Amnon's house and prepare food for him. So Tamar went to her brother Amnon's house, and he was in bed. And she took dough and kneaded it and made cakes in his sight and baked them. She took the pan and emptied it out before him, but he refused to eat. And Amnon said, Send everyone out from me. So everyone went out from him. Then Amnon said to Tamar, Bring the food here into the bedroom, so I may eat from your hand. So Tamar took the cakes she had made and brought them into the room to Amnon her brother. And when she brought them to him, he took hold of her and said, Come lie with me, my sister. She replied, No, my brother! Do not force and humble me, for no such thing should be done in Israel! Do not do this foolhardy, scandalous thing! And I, how could I rid myself of my shame? And you, you will be [considered] one of the stupid fools in Israel. Now therefore, I pray you, speak to the king, for he will not withhold me from you. But he would not listen to her, and being stronger than she, he forced her and lay with her. Then Amnon hated her exceedingly, so that his hatred for her was greater than the love with which he had loved her. And Amnon said to her, Get up and get out! But she said, No! This great evil of sending me away is worse than what you did to me. But he would not listen to her. He called the servant who served him and said, Put this woman out of my presence now, and bolt the door after her! Now [Tamar] was wearing a long robe with sleeves and of various colors, for in such robes were the king's virgin daughters clad of old. Then Amnon's servant brought her out and bolted the door after her. And [she] put ashes on her head and tore the long, sleeved robe which she wore, and she laid her hand on her head and went away shrieking and wailing. And Absalom her brother said to her, Has your brother Amnon been with you? Be quiet now, my sister. He is your brother; take not this matter to heart. So Tamar dwelt in her brother Absalom's house, a desolate woman. But when King David heard of all these things, he was very angry. And Absalom spoke to Amnon neither good nor bad; for Absalom hated Amnon because he had humbled his sister Tamar. After two full years Absalom had sheepshearers at Baal-hazor near Ephraim, and Absalom invited all the king's sons. Absalom came to the king and said, Behold, your servant has sheepshearers; I pray you, let the king and his servants go with your servant. And the king said to Absalom, No, my son, let us not all go, lest we be burdensome to you. Absalom urged David; still he would not go, but he blessed him. Then said Absalom, If not, I pray you, let my brother Amnon go with us. And the king said to him, Why should he go with you? But Absalom urged him, and he let Amnon and all the king's sons go with him. Now Absalom commanded his servants, Notice now, when Amnon's heart is merry with wine and when I say to you, Strike Amnon, then kill him. Fear not; have I not commanded you? Be courageous and brave. And the servants of Absalom did to Amnon as Absalom had commanded. Then all the king's sons arose and every man mounted his mule and fled. While they were on the way, the word came to David, Absalom has killed all the king's sons, and not one of them is left. Then the king arose and tore his garments and lay on the floor; and all his servants standing by tore their clothes. But Jonadab son of Shimeah, David's brother, said, Let not my lord suppose they have killed all the king's sons; for Amnon only is dead. This purpose has shown itself on Absalom's determined mouth ever since the day Amnon humiliated his sister Tamar.

All these were the sons of David, besides the sons of the concubines; and Tamar was their sister.