Kitto's Popular Cyclopedia of Biblial Literature
One´simus (profitable), a slave belonging to Philemon of Colosse, who fled from his master, and proceeded to Rome, where he was converted by St. Paul, who sent him back to his master, a friend and convert of the apostle, with an eloquent letter, the purport of which is described in the article Philemon, Epistle to. Onesimus, accompanied by Tychicus, left Rome with not only this epistle, but with those to the Ephesians and Colossians (). It is believed that Onesimus, anxious to justify the confidence which Paul reposed in him, by appearing speedily before his master, left Tychicus to take the Epistle to the Ephesians; and hastened to Colosse where he doubtless received the forgiveness which Paul had so touchingly implored for him as 'a brother beloved.' An uncertain tradition makes Onesimus to have been bishop of Berea, where he is said to have suffered martyrdom. The part which Paul took in this difficult and trying case is highly honorable to him; while for Onesimus himself, the highest praise is, that he obtained the friendship and confidence of the apostle.
Kitto, John, ed. Entry for 'Onesimus'. "Kitto's Popular Cyclopedia of Biblial Literature". https://www.studylight.org/encyclopedias/eng/kbe/o/onesimus.html.