2 Maccabees 12:44-45

44 For if he were not expecting that those who had fallen would rise again, it would have been superfluous and foolish to pray for the dead.

45 But if he was looking to the splendid reward that is laid up for those who fall asleep in godliness, it was a holy and pious thought. Therefore he made atonement for the dead, so that they might be delivered from their sin.