2 Samuel 16:20-23

Then Absalom said to Ahithophel, “Give your advice. What shall we do?” Ahithophel said to Absalom, “Go in to your father’s concubines, whom he has left to keep the house; then all Israel will hear that you have made yourself odious to your father. The hands of all who are with you will also be strengthened.” So they pitched a tent for Absalom on the roof, and Absalom went in to his father’s concubines in the sight of all Israel. The advice of Ahithophel, which he gave in those days, was as if one inquired of the word of God; so was all the advice of Ahithophel regarded by both David and Absalom.