What does 2 Samuel 13:31 mean?

David has received a false report, and he believes it. Someone has arrived with news from Absalom's feast in the hill country of Ephraim. The messenger reports that Absalom has murdered all of David's sons. David had at least 19 sons who reached adulthood. Such a slaughter would have been a grave blow to any man. In the traditional sign of grief and mourning, David tears the clothes he is wearing and lays face down on the ground. The servants gathered around him do the same thing.

David took this same posture before his infant son with Bathsheba died (2 Samuel 12:16–17). This loss would be greater by far, both personally for David as a father and for his kingdom. The strength of kings was measured, in part, by the number of their sons.

Before an accurate account can reach David, his nephew reassures him. Jonadab insists that Absalom didn't kill all of his half-brothers: just Amnon. Amnon raped Absalom's sister, Tamar, and Absalom has been waiting two years to take revenge (2 Samuel 13:32–33.

We don't know what insider information Jonadab has: if he spoke to Absalom, overhead something, or figured it out on his own. He's known as very crafty, not unlike the serpent in the garden. And when Amnon lay tormented because of his lust for Tamar, it was Jonadab who came up with the plan that allowed Amnon to rape her (2 Samuel 13:1–5).

When news comes that only Amnon is dead, Jonadab reminds David of his words (2 Samuel 13:35). It's unclear what Jonadab's intent is. If he's trying to win political power, it doesn't seem to work; he's not mentioned again.