Philemon is the eighteenth book of the New Testament and the fifty-seventh book of Bible. In this short letter, Paul the apostle requests that Philemon receives his runaway slave back into his household as a fellow believer. The slave, Onesimus, had become a believer while visiting with Paul.
The Epistle was written by Paul, as a letter to Philemon, as well as a woman named Apphia, a man named Archippus and the church that met in Philemon's home. Paul wrote the book while imprisoned, pleading for forgiveness for Philemon's runaway slave, Onesimus. Paul also asks in the letter for Philemon to prepare space for him, for when he is freed from prison.
Significantly, Paul wrote the letter, recording it himself  rather than it being written down some other way.