New Testament

1 Peter 4:6

4 So they are astonished when you do not rush with them into the same flood of wickedness, and they vilify you. 5 They will face a reckoning before Jesus Christ who stands ready to judge the living and the dead. 6 Now it was for this very purpose that the gospel was preached to those who are now dead, so that though they were judged in the flesh by human standards they may live spiritually by God’s standards. 7 For the culmination of all things is near. So be self-controlled and sober-minded for the sake of prayer. 8 Above all keep your love for one another fervent because love covers a multitude of sins.

Date: 60-65 C.E. (If authentic), 80-90 C.E. (If anymous)
* Dates are based on scholarly estimates

Clement of Alexandria Stromata 6.6

And, as I think, the Saviour also exerts His might because it is His work to save; which accordingly He also did by drawing to salvation those who became willing, by the preaching [of the Gospel], to believe on Him, wherever they were. If, then, the Lord descended to Hades for no other end but to preach the Gospel, as He did descend; it was either to preach the Gospel to all or to the Hebrews only. If, accordingly, to all, then all who believe shall be saved, although they may be of the Gentiles, on making their profession there; since God's pun ishments are saving and disciplinary, leading to conversion, and choosing rather the repentance thorn the death of a sinner; and especially since souls, although darkened by passions, when released from their bodies, are able to perceive more clearly, because of their being no longer obstructed by the paltry flesh.

Date: 195 C.E.
* Dates are based on scholarly estimates