John Chrysostom

And then he adds a third consideration, which was of force to set them down. What then is this? that although charity be joined with it, yet not even in that case is this our knowledge perfect. And therefore he adds, "But if any man think that he knoweth any thing, he knoweth nothing yet as he ought to know." This is a mortal blow. "I dwell not," saith he, "on the knowledge being common to all. I say not that by hating your neighbor and by arrogance, you injure yourself most. …

Homily on 1 Corinthians 20 ↗

Theophylact of Ohrid

Here he says something more, namely, that even if knowledge is united with love, it is still imperfect. For no one, be it Peter or Paul, knows anything as it ought to be known. Why then are you puffed up, you who have knowledge without love? For even if you had knowledge together with love, you would still know nothing in perfection.

Commentary on 1 Corinthians ↗

Cyprian

That we must not rashly judge of another. In the Gospel according to Luke: "Judge not, that ye be not judged: condemn not, that ye be not condemned." Of this same subject to the Romans: "Who art thou that judgest another man's servant? to his own master he standeth or falleth. But he shall stand; for God is able to make him stand." And again: "Wherefore thou art without excuse, O every man that judgest: for in that in which thou judgest another, thou condemnest thyself; for thou doest the same things which thou judgest. …

Treatise XII Three Books of Testimonies Against the Jews ↗

Bonaventure

Gratuitous knowledge teaches to know and the manner of knowing. Whence, upon that saying of the Apostle: "If any man think that he knoweth anything, he hath not yet known how he ought to know": Bernard says: "You see that the Apostle does not approve him who knows many things, but the manner of knowing: see that he places all the fruit and utility of knowledge in the manner of knowing. What does he call the manner of knowing? …

Collationes de Septem Donis, Collation 4 ↗