Ambrose of Milan

However, even parents should not be excused for abandoning us, because they have preferred a younger son to an older one. At the same time, care must be taken that no one, while following their example, has an unfair judgment between their children; so that they think one should be loved, the other should be disregarded. For from this fraternal hatred is aroused, and a crime of parricide is made from the despicable gain of money. The same measure of piety should nourish offspring. …

On Jacob and the Blessed Life, Book 2, Chapter II, Section 5 ↗