3:22–4:1 This treatment of slave and free in Colossians is probably related to the subject matter of the letter to Philemon. Onesimus was a runaway slave whom Paul was returning with a letter to his owner Philemon. Onesimus was accompanying Tychicus with the letter to the Colossians (4:7–9), and they were probably carrying the letter to Philemon as well (Introduction to Philemon).