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.

Wesley's Notes

16:22 The top - Of the king's palace, the very place from whence David had gazed upon Bathsheba, chap.11:2, so that his sin was legible in the very place of his punishment. Went in - To one, or some of them. And by so doing did farther make claim to the kingdom; and, as it were, take possession of it. It being usual in the eastern countries to account the wives and concubines of the late king, to belong of right to the successor. Israel - Who saw him go into the tent; and thence concluded, that he lay with them, as he had designed to do. God had threatened by Nathan, that for his defiling Bathsheba, David's own wives should be defiled in the face of the sun. This is now fulfilled: the Lord is righteous; and no word of his shall fall to the ground.

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!