2 Samuel 13:23
And it came to pass after two full years, that Absalom had sheepshearers in Baal-hazor, which is beside Ephraim: and Absalom invited all the king’s sons. And it came to pass after two full years, that Absalom had sheepshearers in Baal-hazor, which is beside Ephraim: and Absalom invited all the king’s sons.
Two full years passed before Absalom avenged the foul wrong done to his sister by having Amnon killed. Throughout that time he concealed his purpose of revenge so that he could strike more surely at the last. The sheepshearing at Baal-hazor to which he invited all the king's sons furnished the feast of the king's sons where the killing took place.
David had permitted Amnon's shameful crime to pass unpunished and unrebuked. At that feast the drunken, incestuous and doubly guilty Amnon was slain by his brother's command. Amnon's crime and Absalom's revenge show David's sons repeating their father's sins. Amnon's death was part of the twofold judgment then meted out to David for his own sin. His sons' sins brought David continual pain and made him feel the injustice he had done to Uriah and Bath-sheba.