I am sending him back to you, sending my very heart.
ὃν ἀνέπεμψά σοι, αὐτόν, τοῦτ’ ἔστιν τὰ ἐμὰ σπλάγχνα·
Ver. 12. Whom I have sent again to you.
By this also he has quenched his anger, by delivering him up. For masters are then most enraged, when they are entreated for the absent, so that by this very act he mollified him the more.
Ver. 12. Thou therefore receive him, that is my own bowels.
And again he has not given the bare name, but uses with it a word that might move him, which is more affectionate than son. He has said, son, he has said, I have begotten him, so that it was probable he would love him much, because he begot him in his trials. For it is manifest that we are most inflamed with affection for those children, who have been born to us in dangers which we have escaped, as when the Scripture says, Woe, Barochabel! and again when Rachel names Benjamin, the son of my sorrow. Genesis 35:18
Thou therefore, he says, receive him, that is my own bowels. He shows the greatness of his affection. He has not said, Take him back, he has not said, Be not angry, but receive him; that is, he is worthy not only of pardon, but of honor. Why? Because he has become the son of Paul.
[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.