2 Samuel 13:39
And the soul of king David longed to go forth unto Absalom: for he was comforted concerning Amnon, seeing he was dead. And the soul of king David longed to go forth unto Absalom: for he was comforted concerning Amnon, seeing he was dead.
Time softened David's grief over Amnon's death, and he was comforted because Amnon was dead. His being comforted was submission to what had happened. Once comforted, his thoughts turned from the dead to the living, to his living son Absalom, and he longed to go forth to him.
Absalom had fled because he feared punishment, the just punishment, for his crime in ordering Amnon's killing. He had fled to Geshur after ordering Amnon's killing. David's refusal to let Absalom return after that flight to Geshur deepened the estrangement between father and son.
His comfort gives no account of Amnon's fate and does not show that he believed Amnon was saved, had been taken to heaven, or would be purified after death. The idea that Amnon was immediately taken to heaven or would be purified after death is only an inference, and it is contradicted by Scripture's teaching that drunkards will not inherit God's kingdom.