Unto Timothy - For an account of Timothy, see Intro. Section 1.
My own son in the faith - Converted to the Christian faith by my instrumentality, and regarded by me with the affection of a father; see notes, 1 Corinthians 4:15. Paul had no children of his own, and he adopted Timothy as a son, and uniformly regarded and treated him as such. He had the same feeling also toward Titus; Titus 1:4; compare Galatians 4:19 note; 1 Thessalonians 2:7, 1 Thessalonians 2:11 notes; and Philemon 1:10 note.
Grace, mercy, and peace, ... - See the notes, Romans 1:7.