Albert Barnes Commentary Philemon 1:19

"I Paul write it with mine own hand, I will repay it: that I say not unto thee that thou owest to me even thine own self besides." — Philemon 1:19 (ASV)

I Paul have written it with my own hand. It has been inferred from this that Paul wrote this entire epistle with his own hand, though this was contrary to his usual practice. Compare Romans 16:22; 1 Corinthians 16:21; Galatians 6:11.

He undoubtedly meant to refer to this as a mark of special favor towards Philemon, and as furnishing security that he would certainly be bound for what he had promised.

I will repay it. I will be security for it. It is not probable that Paul supposed Philemon would rigidly exact it from him, but if he did, Paul would feel himself bound to pay it.

Although I do not say to you how you owe to me your own self besides. Paul had doubtless been the means of Philemon's conversion, and whatever hope Philemon cherished of eternal life was to be traced to Paul's instrumentality. Paul says that this was equivalent to Philemon owing himself to Paul.

Philemon's very life—his eternal welfare—was to be traced to Paul's labors. What Paul now asked of Philemon was a small matter compared with this, and Paul seems to have supposed—what was probably true—that, for this consideration, Philemon would not think of exacting from him what Paul had voluntarily obligated himself to fulfill.