II Samuel 13:26

Then Absalom said, "And not (i.e., if thou doest not go), may my brother Amnon go with me?" The king would not give his consent to this; whether from suspicion cannot be determined with certainty, as he eventually yielded to Absalom's entreaties and let Amnon and all the other king's sons go. From the length of time that had elapsed since Amnon's crime was committed, without Absalom showing any wish for revenge, David might have felt quite sure that he had nothing more to fear. But this long postponement of revenge, for the purpose of carrying it out with all the more certainty, is quite in the spirit of the East.

The righteous God had lately told David, by Nathan the prophet, that, to chastise him for his son in the matter of Uriah, he would "raise up evil against him out of his own house," (Sa2 12:11). And here, in the very next chapter, we find the evil beginning to rise; henceforward he was followed with one trouble after another, which made the latter part of his reign less glorious and pleasant than the former part. Thus God chastened him with the rod of men, yet assured him that his "loving-kindness he would not utterly take away." Adultery and murder were David's sins, and those sins among his children (Amnon defiling his sister Tamar, and Absalom murdering his brother Amnon) were the beginnings of his punishment, and the more grievous because he had reason to fear that his bad example might help to bring them to these wickednesses. In this chapter we have, I. Amnon ravishing Tamar, assisted in his plot to do it by Jonadab his kinsman, and villainously executing it (v. 1-20). II. Absalom murdering Amnon for it (v. 21-39). Both were great griefs to David, and the more because he was unwittingly made accessory to both, by sending Tamar to Amnon and Amnon to Absalom.