Augustine of Hippo

"What is your own opinion? What people do you call happy?" He [the psalmist] would not say, "Happy is the people whose strength is in their own mind." If he had said this, he would, it is true, distinguish that people from the former that made happiness consist in that visible and bodily good fortune, but he would not yet have passed beyond all the vanities and lying follies, for the same Scriptures teach elsewhere: "Cursed be everyone that places his hope in humankind." Therefore, he ought not to place it in himself, because he …

Letter 155 ↗

Jerome

Thus says the Lord: Cursed is the man who trusts (or has hope) in man, and relies on flesh for his strength, and turns his heart away from the Lord. He will be like a shrub in the desert, and will not see when good comes; but he will live in dryness in the desert, in a land of salt and uninhabitable. …

Commentary on Jeremiah ↗

Bernard of Clairvaux

All things which are good, even those of which man is the agent, really come from God rather than man. "It is the spirit," we are told, "that gives life, the flesh has nothing to offer." Hence there is a curse on the man who puts his trust in man, for although our whole hope rightly depends on God made man, it is not because he is man but because he is God.

Sermons on the Song of Songs, Sermon 10 ↗