The Epistle of Paul the Apostle to Philemon is a personal letter in which the apostle beseeches Philemon to take back a runaway slave, Onesimus. The slave had come to Rome, where Paul was being held prisoner, and there had been converted by Paul.

Philemon 1

1:9 Yet for love's sake I rather beseech thee, being such an one as Paul the aged, and now also a prisoner of Jesus Christ.