The Apocalypse of Paul is an account of the apostle's ascent into heaven and what he found there, with instructions for other souls on how to conduct themselves during judgment. One of the most interesting aspects of the text is that it corresponds to events found in the NT and includes references to reincarnations.
Paul explained that he didn't know if he was taken up in his body or in his spirit, but he was in paradise [the third heaven]. Some say that Paul esperienced a NDE when he was stoned and left for dead [see Acts 14:19-20].
Paul describes how each soul must ride as best it can after death through a hierarchy of heavens and ace the increasingly difficult challenges posed by the guardian angels of each heaven. Paul finally reaches the 10th and highest heaven, where he is transformed.