Unto Timothy my own son in the faith
Not in the flesh, or by natural descent, but in a spiritual sense, in the faith of Christ; for Timothy was not related to the apostle according to the flesh, as some have thought, but the relation was spiritual; though the apostle was not properly his spiritual father, or the instrument of his conversion; for Timothy was a converted person, and a disciple of Christ, and well reported of by the brethren, when the apostle first met with him, ( Acts 16:1 Acts 16:2 ) but he calls him his son, either because of his age, being a young man; or because of his affection for him, so the Vulgate Latin version reads, "a beloved son"; or rather, because he was instructed more largely by the apostle into the doctrine of faith; and as a son, with a father, served with him in the Gospel of Christ. It may be rendered "a true or genuine son in the faith", in distinction from nominal Christians, formal professors and hypocrites. Timothy was a real Christian, a true believer, and an hearty and upright professor and preacher of the faith of Christ, as well as truly regenerated by the Spirit of God.
Grace, mercy, and peace from God our Father, and Jesus
the Arabic version reads, "and Lord Jesus Christ our Lord". The form of salutation is the same as in all the epistles of the apostle, only that "mercy" is here inserted; and when he wishes "grace" to Timothy, he may mean a fresh discovery of the love and free favour of God unto him, and an increase of grace in him, and of the gifts of the Spirit upon him; and by "mercy" he may intend a fresh application of the pardoning mercy of God, through Christ, and all assistance, and success in his work as a minister, and all succour and support under every trial and exercise, and mercy at the last day, or the mercy of our Lord Jesus Christ unto eternal life; and by "peace" he may design peace of conscience through the blood of Christ, and all prosperity, temporal, spiritual, and eternal. And all this being wished for equally from Christ, as from God the Father, is a proof of the proper deity of our Lord.