“go in to your father’s concubines.” Ahithophel advised Absalom to have sex with David’s concubines. Culturally, this would make an absolute break between Absalom and David, and show that Absalom was taking David’s place as king. However, Ahithophel’s advice may have had another motivation: Ahithophel was the grandfather of Bathsheba, whom David basically raped, got pregnant, arranged for her husband Uriah to be killed, and then married. Ahithophel may have thought of Absalom having sex with David’s wives as a kind of revenge. (See commentary on 2 Samuel 15:12). The phrase “go in to” is clear enough, meaning to go in to where the concubines were and have sex with them. Ahithophel was not as graphic as saying, “go into” your father’s wives. The women were concubines, but for the purpose of humiliating David, they were his wives.