Clement of Rome

Every kind of honour and happiness was bestowed upon you, and then was fulfilled that which is written, "My beloved ate and drank, and was enlarged and became fat, and kicked." [Deuteronomy 32:15] Hence flowed emulation and envy, strife and sedition, persecution and disorder, war and captivity. So the worthless rose up against the honoured, those of no reputation against such as were renowned, the foolish against the wise, the young against those advanced in years. …

Clement's First Letter to the Corinthians, Chapters 3-4 ↗

Ambrose of Milan

But we shouldn't leave his parents without excuse for having preferred their younger son to the elder. At the same time we must take care so that no one, in turning to their example, would make an unfair judgment between his sons or suppose that he should love the one and esteem the other less. From this line of conduct fraternal hatreds are aroused and the crime of fratricide is contrived to gain a worthless sum of money. Let children be nurtured with an equal measure of devotion. …

On Jacob and the Blessed Life, Book 2, Chapter 2, Sections 5-6 ↗