John Chrysostom

"Wherefore, brethren, be ye steadfast, unmoveable." Just and seasonable is this exhortation after all that had gone before. For nothing so disquiets as the thought that we are buffeted without cause or profit. "Always abounding in the work of the Lord:" i.e., in the pure life. And he said not, "working that which is good," but "abounding;" that we might do it abundantly, and might overpass the lists. "Knowing that your labor is not in vain in the Lord." What sayest thou? Labor again? …

Homily on 1 Corinthians 42 ↗

Theophylact of Ohrid

Since, he says, you have learned that there will be a resurrection and recompense for the good and the wicked, be steadfast; for they were wavering in the teaching about the resurrection. And since they were also neglecting the good life, on account of there supposedly being no resurrection, he says: "always abound in the work of the Lord"; not only do it, but do it in abundance. The "work" "of the Lord," that which the Lord loves and which He requires of us, is virtue. …

Commentary on 1 Corinthians ↗

Thomas Aquinas

1023. – Then when he says, Therefore my beloved brethren, he adds an admonition. For as it was said, the false apostles were destroying the Corinthians by denying the resurrection, and so, after he established faith in the resurrection, and displayed it through examples, he admonishes them to occupy themselves with good, and not be seduced by the false apostles. And concerning this he does three things. …

Commentary on 1 Corinthians ↗