2 Samuel 15:34-37
15:34 But you will be able to counter the advice of Ahithophel if you go back to the city and say to Absalom, ‘I will be your servant, O king! Previously I was your father’s servant, and now I will be your servant.’
15:35 Zadok and Abiathar the priests will be there with you. Everything you hear in the king’s palace you must tell Zadok and Abiathar the priests.
15:36 Furthermore, their two sons are there with them, Zadok’s son Ahimaaz and Abiathar’s son Jonathan. You must send them to me with any information you hear.”
15:37 So David’s friend Hushai arrived in the city, just as Absalom was entering Jerusalem.