2 Samuel 16:21

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.

Ahithophel said unto Absalom. This councillor saw that, now the die was cast, half measures would be inexpedient; and to cut off all possibility of reconciliation between the king and his rebellious son, and thereby ensure the safety of those who had joined the conspiracy, gave this atrocious advice regarding the treatment of the royal women who had been left in charge of the palace. Women being held sacred, are generally left inviolate in the casualties of war. The history of the East affords only one parallel to this infamous outrage of Absalom. Ahithophel's counsel appeared politic, but in reality it was most pernicious-a flagrant breach of the divine law (Leviticus 20:11), a greater crime than that of Reuben, who forfeited his birthright (1 Chronicles 5:1), and sure to draw down upon the perpetrator the execration of all good people. Thus, however, the adultery of David with Bath-sheba was punished by this horrid crime of Absalom, committed apparently in the same palace, according to the denunciation of the prophet (2 Samuel 12:11).