2 Maccabees 12:44

38 Then Judas assembled his army and went to the city of Adullam. As the seventh day was coming on, they purified themselves according to the custom, and kept the sabbath there. 39 On the next day, as had now become necessary, Judas and his men went to take up the bodies of the fallen and to bring them back to lie with their kindred in the sepulchres of their ancestors. 40 Then under the tunic of each one of the dead they found sacred tokens of the idols of Jamnia, which the law forbids the Jews to wear. And it became clear to all that this was the reason these men had fallen. 41 So they all blessed the ways of the Lord, the righteous judge, who reveals the things that are hidden; 42 and they turned to supplication, praying that the sin that had been committed might be wholly blotted out. The noble Judas exhorted the people to keep themselves free from sin, for they had seen with their own eyes what had happened as the result of the sin of those who had fallen. 43 He also took up a collection, man by man, to the amount of two thousand drachmas of silver, and sent it to Jerusalem to provide for a sin offering. In doing this he acted very well and honorably, taking account of the resurrection. 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.

Date: 100-90 B.C.E.
* Dates are based on scholarly estimates
New Testament

1 Corinthians 15:29

20 But now Christ has been raised from the dead, the firstfruits of those who have fallen asleep. 21 For since death came through a man, the resurrection of the dead also came through a man. 22 For just as in Adam all die, so also in Christ all will be made alive. 23 But each in his own order: Christ, the firstfruits; then when Christ comes, those who belong to him. 24 Then comes the end, when he hands over the kingdom to God the Father, when he has brought to an end all rule and all authority and power. 25 For he must reign until he has put all his enemies under his feet. 26 The last enemy to be eliminated is death. 27 For he has put everything in subjection under his feet. But when it says “everything” has been put in subjection, it is clear that this does not include the one who put everything in subjection to him. 28 And when all things are subjected to him, then the Son himself will be subjected to the one who subjected everything to him, so that God may be all in all. 29 Otherwise, what will those do who are baptized for the dead? If the dead are not raised at all, then why are they baptized for them? 30 Why too are we in danger every hour? 31 Every day I am in danger of death! This is as sure as my boasting in you, which I have in Christ Jesus our Lord. 32 If from a human point of view I fought with wild beasts at Ephesus, what did it benefit me? If the dead are not raised, let us eat and drink, for tomorrow we die. 33 Do not be deceived: “Bad company corrupts good morals.” 34 Sober up as you should, and stop sinning! For some have no knowledge of God—I say this to your shame!

Date: 55-57 C.E.
* Dates are based on scholarly estimates