John Wesley on 1 Corinthians 9:17

Willingly - He seems to mean, without receiving anything. St. Paul here speaks in a manner peculiar to himself. Another might have preached willingly, and yet have received a maintenance from the Corinthians. But if he had received anything from them, he would have termed it preaching unwillingly. And so, in the next verse, another might have used that power without abusing it. But his own using it at all, he would have termed abusing it. A dispensation is intrusted to me - Therefore I dare not refrain.