2 Samuel 16:20-23 King James Version (KJV)
20 Then said Absalom to Ahithophel, Give counsel among you what we shall do.
21 And Ahithophel said unto Absalom, Go in unto thy father's concubines, which he hath left to keep the house; and all Israel shall hear that thou art abhorred of thy father: then shall the hands of all that are with thee be strong.
22 So they spread Absalom a tent upon the top of the house; and Absalom went in unto his father's concubines in the sight of all Israel.
23 And the counsel of Ahithophel, which he counselled in those days, was as if a man had enquired at the oracle of God: so was all the counsel of Ahithophel both with David and with Absalom.
2 Samuel 16:20-23 New International Version (NIV)
20 Absalom said to Ahithophel, “Give us your advice. What should we do?”
21 Ahithophel answered, “Sleep with your father’s concubines whom he left to take care of the palace. Then all Israel will hear that you have made yourself obnoxious to your father, and the hands of everyone with you will be more resolute.” 22 So they pitched a tent for Absalom on the roof, and he slept with his father’s concubines in the sight of all Israel.
23 Now in those days the advice Ahithophel gave was like that of one who inquires of God. That was how both David and Absalom regarded all of Ahithophel’s advice.