Jehu continued his slaughtering conquest in the book of 2 Kings, chapter 10.
First, he sought the 70 sons of the Ahab in Samaria. He contacted the guardians of the sons to gather the best of their people. These were, of course, Ahab's sons. Jehu's servants then had them beheaded and their heads put in baskets.
Next, he went to Judah and gathered the relatives of the previous king whom he had slaughtered. He then had them tossed in a pit and killed.
Lastly, he assembled all of the worshipers of Baal, including the Baal prophets. He brought them into the house of Baal, then surrounded the house with his armed servants. Then, all of them were put to the sword.
Once this was complete, and all of the other false worshipers were destroyed, God was pleased with Jehu for his accomplishments. He reigned over Israel for 28 years.