Jamieson, Fausset and Brown on Philemon 1:15

15. perhaps--speaking in human fashion, yet as one believing that God's Providence probably (for we cannot dogmatically define the hidden purposes of God in providence) overruled the past evil to ultimately greater good to him. This thought would soften Philemon's indignation at Onesimus' past offense. So Joseph in Ge 45:5.

departed--literally, "was parted from thee"; a softening term for "ran away," to mitigate Philemon's wrath.

receive him--Greek, "have him for thyself in full possession" (see on Php 4:18). The same Greek as in Mt 6:2.

for ever--in this life and in that to come (compare Ex 21:6). Onesimus' time of absence, however long, was but a short "hour" (so Greek) compared with the everlasting devotion henceforth binding him to his master.