Philemon 1:10

(10) My son. — Properly, my own child, whom I have begotten in my bonds, Onesimus. The name is withheld, till Philemon’s interest is doubly engaged, for one who is the Apostle’s “own child” (a name of endearment given elsewhere only to Timothy and Titus), and for one who was begotten under the hardships and hindrances of imprisonment. At last the name is given, and even then comes, in the same breath, the declaration of the change in him from past uselessness to present usefulness, both to the Apostle and to his former master.

Onesimus. — Of Onesimus we know absolutely nothing, except what we read here and in Colossians 4:9. Tradition, of course, is busy with his name, and makes him Bishop of Berœa, in Macedonia, or identifies him with the Onesimus, Bishop of Ephesus, mentioned in the Ignatian Epistle to the Ephesians (Ephesians 1:2). The name was a common one, especially among slaves.