And if any one strive He now speaks of perseverance, that no man may think that he has done enough when he has been engaged in one or two conflicts. He borrows a comparison from wrestlers, not one of whom obtains the prize till he has been victorious in the end. Thus he says: "In a race all run, but one obtaineth the prize; run so that ye may obtain." (1-Corinthians 9:24.) If any man, therefore, wearied with the conflict, immediately withdraw from the arena to enjoy repose, he will be condemned for indolence instead of being crowned. Thus, because Christ wishes us to strive during our whole life, he who gives way in the middle of the course deprives himself of honor, even though he may have begun valiantly. To strive lawfully is to pursue the contest in such a manner and to such an extent as the law requires, that none may leave off before the time appointed.

And if a man also strive for masteries - As in the Grecian games. See this favorite illustration of Paul explained in the notes at 1-Corinthians 9:24 ff.
Yet is he not crowned, except he strive lawfully - In conformity with the rules of the games. See Grotius, in loc. No one could obtain the prize unless he had complied with all the laws of the games, and had thus given to those with whom he contended, a fair opportunity to succeed. "In those contests, he who transgressed the rules in the least matter, not only failed of the prize, even though the apparent victor, but was sometimes disgraced and punished." Pictorial Bible. So the apostle here represents the Christian minister as engaged in a struggle or conflict for the crown. He says that he could not hope to win it unless he should comply with all the laws by which it is conferred; unless he should subdue every improper propensity, and make an effort like that evinced by the combatants at the Olympic games; compare the notes at 1-Corinthians 9:26-27.

If a man also strive for masteries - Εαν δε και αθλῃ τις· If a man contend in the public games - the Olympic or Isthmian games among the Greeks, so often alluded to and particularly explained in the notes on 1-Corinthians 9:24-26, to which the reader is referred for a full illustration of this verse.
Is he not crowned - Though he may have conquered, except he strive lawfully - unless he enter according to the rules of the athlete, and act as these direct. No man, however zealous he may have been, is to expect the Well done, good and faithful servant, from Jesus Christ, unless he have labored in the word and doctrine, preached the truth as it is in Jesus, and built up the Church upon Him who is its only Foundation.

(3) And if a man also strive for masteries, [yet] is he not crowned, except he strive lawfully.
(3) The third admonition: the ministry is similar to a game in which men strive for the victory, and no man is crowned, unless he strive according to the laws which are prescribed, be they ever so hard and painful.

And if a man also strive for masteries,.... In the Olympic games, by running, wrestling, leaping, &c.
yet is he not crowned; with a corruptible, fading crown, a crown made of herbs and leaves of trees, as parsley, laurel, &c.
except he strive lawfully; according to the laws and rules fixed for those exercises; so no man that calls himself a Christian, minister, or any other, can expect the crown of life, the prize of the high calling of God, except he runs the race set before him, in the right way; looking to Christ, the mark, pressing through all difficulties, towards the prize, and holds on and out unto the end.

And--"Moreover."
strive for masteries--"strive in the games" [ALFORD]; namely, the great national games of Greece.
yet is he not crowned, except--even though he gain the victory.
strive lawfully--observing all the conditions of both the contest (keeping within the bounds of the course and stript of his clothes) and the preparation for it, namely, as to self-denying diet, anointing, exercise, self-restraint, chastity, decorum, &c. (1-Corinthians 9:24-27).