The Apostle Paul
1 Corinthians 15:58ESV·traditional attribution

Therefore, my beloved brothers, be steadfast, immovable, always abounding in the work of the Lord, knowing that in the Lord your labor is not in vain.

John Calvin Reformed @genevareformer

58. Wherefore, my brethren Having satisfied himself that he had sufficiently proved the doctrine of the resurrection, he now closes his discussion with an exhortation; and this has much more force, than if he had made use of a simple conclusion with an affirmation.

Matthew Henry Presbyterian @wholebiblehenry

In this verse we have the improvement of the whole argument, in an exhortation, enforced by a motive resulting plainly from it. I. An exhortation, and this threefold: - 1. That they should be stedfast - hedraioi, firm, fixed in the faith of the gospel, that gospel which he had preached and they had received, namely, That Christ died for our sins, and arose again...

Albert Barnes Presbyterian @notesbybarnes

Verse 58. Therefore, my beloved brethren. In view of the great and glorious truths which have been revealed to us respecting the resurrection. Paul closes the whole of this important discussion with an exhortation to that firmness in the faith which ought to result from truths so glorious, and from hopes so elevated as these truths are fitted to impart.