John Calvin Commentary 1 Corinthians 15:58

"Wherefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labor is not vain in the Lord." — 1 Corinthians 15:58 (ASV)

Therefore, my brothers, having satisfied himself that he had sufficiently proven the doctrine of the resurrection, he now closes his discussion with an exhortation; and this has much more force than if he had used a simple conclusion with an affirmation. Since your labor, he says, is not in vain in the Lord, be steadfast, and abound in good works. Now he says that their labor is not in vain, for this reason: that there is a reward laid up for them with God. This is that exclusive hope which, initially, encourages believers and afterward sustains them, so that they do not stop short in the race. Therefore, he exhorts them to remain steadfast, because they rest on a firm foundation, as they know that a better life is prepared for them in heaven.

He adds — abounding in the work of the Lord; for the hope of a resurrection keeps us from becoming weary in well-doing, as he teaches in Colossians 1:10. For amid so many causes of stumbling that we constantly encounter, who would not lose heart, or turn aside from the way, if it were not that by thinking of a better life, he is in this way kept in the fear of God? Now, on the other hand, he suggests that if the hope of a resurrection is taken away, then, the foundation (as it were) being rooted up, the whole structure of piety falls to the ground. Unquestionably, if the hope of reward is taken away and extinguished, eagerness in running will not only grow cold but will be completely destroyed.