2 Samuel 13:12
And she answered him, Nay, my brother, do not force me; for no such thing ought to be done in Israel: do not thou this folly. And she answered him, Nay, my brother, do not force me; for no such thing ought to be done in Israel: do not thou this folly.
In the verse Tamar resists Amnon as he attempts to force himself upon her. The act he intends is a shameful, foul, unnatural and incestuous crime of adultery. As the first-born, Amnon is doubly guilty under the law that pronounces death upon the adulterer.
David, self-condemned by his own sin, lets the crime pass unpunished and unrebuked and fails to bring the offender to justice. Absalom, the natural protector of his sister so foully wronged, conceals his purpose of revenge for two full years and then has the drunken, incestuous Amnon slain by his brother's command at a feast of the king's sons. The account of Amnon's great crime shows the bitter consequences of David's wrongdoing, with his sons repeating sin within his own family. By the crime going unpunished and by Amnon's slaying, twofold judgment is meted out to David.