The book of Philemon contains only one chapter, and was written to Philemon by Paul, while in he was in Prison.
Paul writes to Philemon and gives his greetings, appreciation and gratitude to him. Paul goes on to mention Onesimus, who was a runaway slave of Philemon who lived in Colosse (see Colossians 4:9) Paul writes to Philemon; “I beseech thee for my son Onesimus, whom I have begotten in my bonds; Which in time past was to thee unprofitable, but now profitable to thee and to me.” (Philemon 1:10-11)
Onesimus had run away and traveled to Rome where he met Paul. While there, Onesimus surrendered his life to Christ. Under Roman Law, Philemon could execute his slave for running away. Paul writes this letter to Philemon to plead with Philemon to accept his plea. However, Paul goes beyond this and asks Philemon to also accept Onesimus as a brother in Christ and to overlook his faults and errors. “For perhaps he therefore departed for a season, that thou shouldest receive him forever; Not now as a servant, but above a servant, a brother beloved, specifically to me, but how much more unto thee, both in the flesh and in the Lord?” (Philemon 1:15-16)