2 Kings 10:15

10:15 When he left there, he met Jehonadab, son of Rekab, who had been looking for him. Jehu greeted him and asked, “Are you as committed to me as I am to you?” Jehonadab answered, “I am!” Jehu replied, “If so, give me your hand.” So he offered his hand and Jehu pulled him up into the chariot.

2 Kings 10:23-24

10:23 Then Jehu and Jehonadab son of Rekab went to the temple of Baal. Jehu said to the servants of Baal, “Make sure there are no servants of the Lord here with you; there must be only servants of Baal.” 10:24 They went inside to offer sacrifices and burnt offerings. Now Jehu had stationed eighty men outside. He had told them, “If any of the men inside get away, you will pay with your lives!”