2 Samuel 13:23 Two years later, when Absalom’s sheepshearers were at Baal Hazor near the border of Ephraim, he invited all the king’s sons to come there. 24 Absalom went to the king and said, “Your servant has had shearers come. Will the king and his attendants please join me?”

25 “No, my son,” the king replied. “All of us should not go; we would only be a burden to you.” Although Absalom urged him, he still refused to go but gave him his blessing.

26 Then Absalom said, “If not, please let my brother Amnon come with us.”

The king asked him, “Why should he go with you?” 27 But Absalom urged him, so he sent with him Amnon and the rest of the king’s sons.

28 Absalom ordered his men, “Listen! When Amnon is in high spirits from drinking wine and I say to you, ‘Strike Amnon down,’ then kill him. Don’t be afraid. Haven’t I given you this order? Be strong and brave.” 29 So Absalom’s men did to Amnon what Absalom had ordered. Then all the king’s sons got up, mounted their mules and fled.

30 While they were on their way, the report came to David: “Absalom has struck down all the king’s sons; not one of them is left.” 31 The king stood up, tore his clothes and lay down on the ground; and all his attendants stood by with their clothes torn.

32 But Jonadab son of Shimeah, David’s brother, said, “My lord should not think that they killed all the princes; only Amnon is dead. This has been Absalom’s express intention ever since the day Amnon raped his sister Tamar. 33 My lord the king should not be concerned about the report that all the king’s sons are dead. Only Amnon is dead.”

34 Meanwhile, Absalom had fled.

Now the man standing watch looked up and saw many people on the road west of him, coming down the side of the hill. The watchman went and told the king, “I see men in the direction of Horonaim, on the side of the hill.”(b)

35 Jonadab said to the king, “See, the king’s sons have come; it has happened just as your servant said.”

36 As he finished speaking, the king’s sons came in, wailing loudly. The king, too, and all his attendants wept very bitterly.

37 Absalom fled and went to Talmai son of Ammihud, the king of Geshur. But King David mourned many days for his son.

38 After Absalom fled and went to Geshur, he stayed there three years. 39 And King David longed to go to Absalom, for he was consoled concerning Amnon’s death.

b. 2 Samuel 13:34 Septuagint; Hebrew does not have this sentence.

Absolom waited two years to get his revenge. I know revenge is wrong; but isn't this part of the calamity that Nathan warned David about after David had Uriah murdered to cover up David's affair with Uriah's wife Bathsheba?

David had been furious. Absolom was furious. Good old Uncle Jonadab, though, reminds me of Dr. Smith on the Lost in Space series. First he helped his nephew Amnon set up the circumstances that led to the rape of his niece Tamar, then he was there to report when David's sons who were unwittingly the cover for Absolom's revenge on Amnon returned. Absolom had to leave town after the revenge and David missed his son Absolom... and he understood why Absolom did what he did.

This is from Bible.org.

I doubt very much that Absalom wants David to attend the celebration in Baal-Hazor, nearly 20 miles away to the north and east of Jerusalem. It is a trek David will not wish to make, and I believe Absalom knows it. Besides, David and his entourage will be a large group, too large to be easily accommodated. And so David declines, but gives Absalom his blessing. Absalom expected this response, and he does not give up. He now presses David for what he really wants -- he wants David to send his son Amnon. Is Absalom implying that Amnon can represent David as his first-born? We do not know because we are not told.

David wonders, though. Why would Absalom ask specifically for Amnon to come? David presses Absalom on this point, but he seems to avoid the question and continue to press his father to send him. Is it David's idea to send all his sons along with Absalom? Perhaps. This will certainly seem to put some of David's suspicions to rest. One way or the other, David stays home (oh boy, is this deja vu?) sending his sons in his place.

I don't like what I see of Jonadab in this chapter. He may have been a very shrewd fellow, but he seems to be an opportunist with no scruples. He must have had an idea what Amnon had in mind with regard to Tamar, but he did nothing to stop him. Instead, he told him how he could achieve his evil purpose. And now, having been an accessory before the fact in the rape of Tamar, he adds to his sin by knowing about Absalom's plan to kill Amnon and yet doing nothing about it. (Frankly, I'm surprised he didn't tell Absalom how to get Amnon out to the ranch.) And beyond this, he now uses this knowledge to try to further his own standing with David. It seems that he has a very shrewd reason for telling David that only Amnon has died, before David's sons return to Jerusalem. Their arrival proves that Jonadab knows what he is talking about. When they arrive, Jonadab says to David, “See, didn't I tell you this ahead of time? Things took place just as I told you they would” (verse 35). I think Jonadab is trying to make points with David.

Shortly after Jonadab assures David that only one son is dead, the watchman look out and see that many men are coming. Soon, all of David's sons but two arrive in Jerusalem: Amnon who is dead, and Absalom who kills him and flees. The weeping is commenced by David's sons this time, and David joins with them in mourning the death of Amnon. They all weep bitterly.

This is from the blueletterbible.org site.

Absalom has killed all the king’s sons, and not one of them is left: It is significant that David did not react to this news with disbelief. He sensed that Absalom was capable of such evil. David reacted with mourning instead of disbelief.

Let not my lord suppose they have killed all the young men: Jonadab brought the “good” news to David that only Amnon is dead, and dead because he forced his sister Tamar. Jonadab probably hoped to gain favor with David by bringing this more favorable news, but God knew that Jonadab set the whole course of events in motion with his wicked advice to Amnon (2 Samuel 13:3-5).

The king and all his servants wept very bitterly: David is rightly grieved at learning of the death of his eldest son, the Crown Prince Amnon. Yet David’s lack of correction against Amnon contributed to this murder. If David had administered Biblical correction according to Exodus 22:16-17 and Deuteronomy 22:28-29, Absalom would not have felt so free to administer his own brutal correction.

Sorry I have to say something about the commentary from blueletterbible.org. It says if David had administered the "Biblical Corrections" then Absolom would not have felt so free to kill his step brother Amnon for the Rape of Tamar. I've read Exodus 22 and Deuteronomy 22. Amnon would have been required to marry Tamar or provide financially for her for the rest of her life. That's the "correction" that the commentary uses. Tamar would lose either way. She was tied to her rapist either way. One correction would have left her in a loveless marriage to her step brother. She probably wouldn't have had children since he was so hateful. This way her rapist is dead and her brother has fled and she will never marry or have children.