A.T. Robertson Commentary Philemon 1:20

"Yea, brother, let me have joy of thee in the Lord: refresh my heart in Christ." — Philemon 1:20 (ASV)

Let me have joy of thee (εγω σου οναιμην). Second aorist middle optative of ονινημ, old verb, only here in N.T. Optative the regular construction for a wish about the future. "May I get profit from thee in the Lord."

Refresh my heart in Christ (αναπαυσον μου τα σπλαγχνα εν Χριστω). See verse 7 for αναπαυσον (first aorist active imperative of αναπαυω) and σπλαγχνα (3 times in this letter, 7,12,20).