“Thus King Jehu wiped out Baal from Israel. But King Jehu did not turn aside from the sins of King Jeroboam son of Nebat, which he caused Israel to commit. He left the golden calves that were in Bethel and Dan. Yahweh said to King Jehu. ‘Because you have done well in carrying out what I consider right, and in accordance with all that was in my heart, having dealt with the house of King Ahab, your sons of the fourth generation shall sit on the throne of Israel.’ But King Jehu was not careful to follow the law of Yahweh the God of Israel with all his heart. He did not turn from the sins of King Jeroboam, which he caused Israel to commit.”
You would think that King Jehu would get a special reward for his success in wiping out the Baal worship. However, he was not perfect. He still left the golden calves in Bethel and Dan. He still walked in the evil ways of King Jeroboam. However, he was good enough to have his sons to the 4th generation sit on the throne of Israel, but not longer.