2 Machabees (Maccabees) 12:41-46

Then they all blessed the just judgment of the Lord, who had discovered the things that were hidden. And so betaking themselves to prayers, they besought him, that the sin which had been committed might be forgotten. But the most valiant Judas exhorted the people to keep themselves from sin, forasmuch as they saw before their eyes what had happened, because of the sins of those that were slain. And making a gathering, he twelve thousand drachms of silver to Jerusalem for sacrifice to be offered for the sins of the dead, thinking well and religiously concerning the resurrection, (For if he had not hoped that the that were slain should rise again, it would have seemed superfluous and vain to pray for the dead,) And because he considered that the who had fallen asleep with godliness, had great grace laid up for them. It is therefore a holy and wholesome thought to pray for the dead, that they may be loosed from sins.