Dates: c. 107 · Wikipedia
Summary: Ignatius of Antioch, writing to the churches while in chains on his way to martyrdom (d. c. 107), gives one of the earliest hints of Christ's descent: the prophets who awaited Christ as their Teacher were, at his coming, "raised … from the dead" — presupposing that the righteous dead of the old covenant were held below until Christ came to them.
that we may be found the disciples of Jesus Christ, our only Master—how shall we be able to live apart from Him, whose disciples the prophets themselves in the Spirit did wait for Him as their Teacher? And therefore He whom they rightly waited for, being come, raised them from the dead.
— Epistle to the Magnesians, ch. 9, historicalchristian.faith. Ignatius's point is christological and polemical (against keeping the Sabbath "after the Jewish manner"): the very prophets foresaw Christ "in the Spirit" and waited for Him as Teacher. His closing clause — that at His coming He "raised them from the dead" — presupposes that those righteous dead were detained in the realm of the dead until Christ descended to them and brought them up. This is the descent in seed form: an early, implicit witness, not yet the developed geography of a two-compartment Hades, and Ignatius offers no description of its structure.