Augustine of Hippo

What could be briefer, truer, better for the soul to know? For this is all a person is—a keeper of God's commandments. Not being such, he is, so to say, nothing at all, because instead of being constantly reshaped to the image of the truth, he remains bogged down in the likeness of shadow.

City of God 20.3 ↗

Jerome

"Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man. For God shall bring every work into judgement, with every secret thing, whether it be good, or whether it be evil. "The Hebrews say that although it used to be among other writings of Solomon in the past, they have not persisted in memory; and this book seems as if it ought to have been omitted, because it asserts that all God's creations are vain and that he thinks everything is done for nothing, and he prefers …

Commentary on Ecclesiastes ↗

Gregory the Dialogist

Solomon's book in which these words appear is called Ecclesiastes. Translated, this name means "Preacher." Now, in preaching one expresses sentiments that tend to quiet a noisy crowd. And when there are many people holding opinions of various kinds, they are brought into harmony by the reasoning of the speaker. …

Dialogues, Book 4, Chapter 4 ↗