Verse 21. "Go in unto thy father's concubines" - It may be remembered that David left ten of them behind to take care of the house, see chap. xv. 16. Ahithophel advised this infernal measure, in order to prevent the possibility of a reconciliation between David and his son; thus was the prophecy to Nathan fulfilled, chap. xii. 11. And this was probably transacted in the very same place where David's eye took the adulterous view of Bath-sheba; see chap. xi. 2.
The wives of the conquered king were always the property of the conqueror; and in possessing these, he appeared to possess the right to the kingdom. Herodotus informs us that Smerdis, having seized on the Persian throne after the death of Cambyses, espoused all the wives of his predecessor, lib. iii., c. 68. But for a son to take his father's wives was the sum of abomination, and was death by the law of God, Lev. xx. 11.
This was a sin rarely found, even among the Gentiles.
Every part of the conduct of Absalom shows him to have been a most profligate young man; he was proud, vindictive, adulterous, incestuous, a parricide, and, in fine, reprobate to every good word and work. We still however recollect that David had grievously sinned, and we should also recollect that he suffered grievously for it; and that his humiliation, repentance, and amendment, were most decisive and exemplary. Reader, God is as just as he is merciful.