I would have been glad to keep him with me, in order that he might serve me on your behalf during my imprisonment for the gospel;
ὃν ἐγὼ ἐβουλόμην πρὸς ἐμαυτὸν κατέχειν, ἵνα ὑπὲρ σοῦ μοι διακονῇ ἐν τοῖς δεσμοῖς τοῦ εὐαγγελίου,
Ver. 13. Whom I would have retained with me, that in your stead he might have ministered unto me in the bonds of the Gospel.
Do you see after how much previous preparation, he has at length brought him honorably before his master, and observe with how much wisdom he has done this. See for how much he makes him answerable, and how much he honors the other. You have found, he says, a way by which you may through him repay your service to me. Here he shows that he has considered his advantage more than that of his slave, and that he respects him exceedingly.
[For moral, see Phm 1:16]
Haydock Catholic Bible Commentary: Philemon
Do thou receive him as my own bowels. That is, as myself. Perhaps by the permission of God's providence (who never permits evil, but for some greater good) he departed from thee for a little while, that thou mightest receive him for ever, being now after his conversion in a way of being made partaker with thee of the same eternal happiness. Wi.