The letter to Philemon, like that to Ephesus and Colosse, was written during Paul's first Roman imprisonment. Timothy was with him, though not himself a prisoner (see note on Colossians 1:1). All three letters were probably carried by the same messenger, probably Tychicus (Colossians 4:7,8), along with Onesimus (Colossians 4:9; Philemon 10).

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8