A.T. Robertson Commentary Philemon 1:5

"hearing of thy love, and of the faith which thou hast toward the Lord Jesus, and toward all the saints;" — Philemon 1:5 (ASV)

Hearing (ακουων). Through Epaphras (Colossians 1:7,8; 4:12), possibly from Onesimus also.

And towards all the saints (κα εις παντας τους αγιους). He spoke of "thy love and faith" (σου την αγαπην κα την πιστιν) "towards the Lord Jesus" (προς τον Κυριον Ιησουν) and by a sort of momentum (Vincent) he carries both words over to the saints, though it can be explained as chiasm (Galatians 4:4) also.