For if I do this thing willingly
That is, not freely and without receiving anything for preaching, without seeking any temporal profits and advantages; nor in pure love to Christ, and the good of souls, without any fear of punishment, or hope of reward; but the apostle supposes a case which was not, and his sense is, that supposing no necessity had been laid upon him, or any injunction or command given him to preach the Gospel, but he had entered on it without any obligation upon him, then, says he,
I have a reward;
or should have one, or might expect one; so the Jews F17 say, that a reward is given to him, who does anything unbidden:
but if against my will,
a dispensation of the Gospel is committed to me;
which was his case; the Gospel was committed to his trust, as anything is to the trust and charge of a steward by his lord, who is obliged to take care of it, and is accountable for it, and of whom faithfulness is required; he did not undertake this economy, or dispensation of the Gospel of himself, of his own mind and will, but it was enjoined him by one that had the command over him, and could and did oblige him to take the charge of it; though he made him willing, as well as able to do it: and therefore since this was the case, that it was not at his own option whether he would preach the Gospel or not, but he was obliged to it by one, that had a superior power and influence over him; hence, though he performed it ever so well, and with never so much faithfulness and integrity, he asks in the following verse,
F17 Maimon. apud Hammond in loc.