The New Testament book of Philemon, specifically a letter written by Paul, identified as a prisoner, to Philemon, a Christian brother. The core of the letter is an appeal from Paul regarding Onesimus, a person who was formerly a slave to Philemon but is now described as a "son" to Paul and "useful" to both men. Paul requests that Philemon welcome Onesimus back, not merely as a slave, but as a "dear brother" in Christ, and even offers to personally pay back any debts Onesimus might owe. The letter also expresses Paul's confidence in Philemon's obedience and his hope to visit soon.