Albert Barnes Commentary Philemon 1:23

"Epaphras, my fellow-prisoner in Christ Jesus, saluteth thee;" — Philemon 1:23 (ASV)

There salute thee Epaphras. The same persons who are mentioned here as greeting Philemon are mentioned at the end of the epistle to the Colossians—furnishing a high degree of evidence that Philemon resided at Colossae. Epaphras was a member of the church there. (See Barnes on Colossians 4:12).

My fellow-prisoner in Christ Jesus. In the cause of Christ. (See Barnes on Philemon 1:1).

The circumstance of his being a prisoner is not mentioned in the parallel passage in the epistle to the Colossians, but nothing is more probable.