2 Samuel 13:6
So Amnon lay down, and made himself sick: and when the king was come to see him, Amnon said unto the king, I pray thee, let Tamar my sister come, and make me a couple of cakes in my sight, that I may eat at her hand. So Amnon lay down, and made himself sick: and when the king was come to see him, Amnon said unto the king, I pray thee, let Tamar my sister come, and make me a couple of cakes in my sight, that I may eat at her hand.
This verse stands at the beginning of the account of Amnon's shameful, incestuous crime against his sister Tamar. As unnatural adultery committed by the first-born, the act made Amnon doubly guilty and deserving of death under the law. David permitted the crime to pass unpunished and unrebuked, because his own sin self-condemned him and kept him from bringing the offender to justice. The wrongdoing became part of the bitter consequences of David's sin, in which his sons repeated sins like those David himself had committed.
After two full years Absalom avenged his foully wronged sister. As her natural protector he acted when the drunken Amnon was slain by his brother's command. The killing took place at a feast of the king's sons. By it twofold judgment was brought upon David for his own sin.