2 Kings 10:15-17

15And when he departed from there, he met Jehonadab the son of Rechab coming to meet him. And he greeted him and said to him, "Is your heart true to my heart as mine is to yours?" And Jehonadab answered, "It is." Jehu said, "If it is, give me your hand." So he gave him his hand. And Jehu took him up with him into the chariot.

16And he said, "Come with me, and see my zeal for the Lord." So he had him ride in his chariot.

17And when he came to Samaria, he struck down all who remained to Ahab in Samaria, till he had wiped them out, according to the word of the Lord that he spoke to Elijah.