John Chrysostom
Again he does not simply use his name, but adds a persuasive expression, one tenderer than the word "son." Thus he called him son when he said, "whom I have begotten."
He suggested that Onesimus must be loved especially because he was born amid temptations. It is known that we have a special love for children born amid dangers from which we have escaped.
Scripture bears witness to this when it says, "Ichabod" (1 Sam 4:21), and when Rachel calls Benjamin "son of my sorrow" (Gen 35:18).
"But receive him as my own heart." By this he expresses his great love for him. He did not say, Take him. He did not say, Do not be angry.
He said, "Receive him." That is, he is worthy not only of forgiveness, but also of honor. Why? Because he has become Paul's son.