2 Samuel 13:26-28

Then said Absalom, If not, I pray thee, let my brother Amnon go with us. And the king said unto him, Why should he go with thee? But Absalom pressed him, that he let Amnon and all the king's sons go with him. Now Absalom had commanded his servants, saying, Mark ye now when Amnon's heart is merry with wine, and when I say unto you, Smite Amnon; then kill him, fear not: have not I commanded you? be courageous, and be valiant.