In 2 Kings 9, the prophet Elisha sends one of the sons of the prophets to anoint Jehu as the king of Israel. The young prophet delivers the message and pours oil on Jehu's head, proclaiming that he has been chosen by the Lord to bring judgment upon the house of Ahab.
Jehu immediately sets out to fulfill his mission. He rides to Jezreel, where King Joram of Israel and King Ahaziah of Judah are recovering from injuries. When Joram learns of Jehu's arrival, he goes out to meet him, suspecting nothing. Jehu shoots Joram with an arrow, killing him, and then proceeds to kill Ahaziah as well.
Jehu enters Jezreel, and Jezebel, the wicked queen mother of Ahab, hears of his coming. She adorns herself and looks out from a window, but Jehu orders her eunuchs to throw her down. Jezebel is killed, and her body is trampled upon by horses.
Jehu then orders the destruction of all of Ahab's descendants, as well as any who remain loyal to Ahab. He kills all the relatives and acquaintances of Ahab, leaving no survivors. Jehu also destroys the temple of Baal and turns it into a latrine.
Despite these actions, Jehu is commended by God for carrying out His judgment against the house of Ahab. However, the chapter concludes by noting that Jehu did not fully follow the law of the Lord and allowed the worship of golden calves to continue in Israel.