Charles Ellicott Commentary Philemon 1:14

"but without thy mind I would do nothing; that thy goodness should not be as of necessity, but of free will." — Philemon 1:14 (ASV)

That thy benefit should not be . . .—The benefit derived from the service of Onesimus St. Paul acknowledges as coming from Philemon, because given with his consent. He will not keep Onesimus and ask that consent by letter, lest it should be as it were of necessity: i.e., lest it should wear even the semblance of constraint.