2 Kings 10:17
And when he came to Samaria, he slew all that remained unto Ahab in Samaria, till he had destroyed him, according to the saying of the LORD, which he spake to Elijah. And when he came to Samaria, he slew all that remained unto Ahab in Samaria, till he had destroyed him, according to the saying of the LORD, which he spake to Elijah.
When Jehu entered Samaria he put to death all who still remained to Ahab there, continuing until he had utterly destroyed them. This was done in fulfillment of the word of the Lord that had been spoken to Elijah concerning Ahab's house. The slaughter in Samaria belonged to Jehu's stern work of reform. By it the dynasty of Ahab was brought to its end.
The zeal with which Jehu executed that judgment upon Ahab's house was mingled with self-exaltation. It was also marked by harshness of speech. His course therefore stands as a warning that zeal in carrying out God's judgment must not be left to exalt self. Such zeal must instead be ruled by humility and by Christlike gentleness.