And {k} 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.

(k) Suspecting the change of the kingdom, and so his own overthrow, he gives such counsel as might most hinder his father's reconciliation: and also declare to the people that Absalom was in highest authority.

Wesley's Notes

16:21 Go - This counsel he gave, partly to revenge the injury done to Bathsheba, the daughter of Eliam, 2Sam 11:3, who was the son of Ahithophel, chap.23:34, and principally for his own, and the people's safety, that the breach between David and Absalom might be irreparable. For this would provoke David in the highest degree and cut of all hope of reconciliation, which otherwise might have been expected by some treaty between Absalom and his tender - hearted father. But in that case his followers, and especially Ahithophel, had been left to David's mercy, and therefore obliged to prosecute the war with all vigour, and to abandon all thoughts of peace: as knowing that his father, though be might dissemble, yet would never forgive so foul a crime. Be strong - They will fight with greater courage and resolution, when they are freed from the fear of thy reconciliation, which otherwise would make their hearts faint, and hands slack in thy cause. But by this we may see the character of Absalom's party, and how abominably wicked they were, whom such a scandalous action tied the faster to him. And we may farther learn, how corrupt the body of the people was, how ripe for that judgment which is now hastening to them.

Jamieson-Fausset-Brown Bible Commentary

21. Ahithophel said unto Absalom-This councillor saw that now the die was cast; half measures would be inexpedient. To cut off all possibility of reconciliation between the king and his rebellious son, he 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.

Matthew Henry's Concise Commentary

16:15-23 The wisest counsellors of that age were Ahithophel and Hushai: Absalom thinks himself sure of success, when he has both; on them he relies, and consults not the ark, though he had that with him. But miserable counsellors were they both. Hushai would never counsel him to do wisely. Ahithophel counselled him to do wickedly; and so did as effectually betray him, as he did, who was designedly false to him: for they that advise men to sin, certainly advise them to their hurt. After all, honesty is the best policy, and will be found so in the long run. Ahithophel gave wicked counsel to Absalom; to render himself so hateful to his father, that he would never be reconciled to him; this cursed policy was of the devil. How desperately wicked is the human heart!