"El hombre de conocimiento debe ser capaz no sólo de amar a sus enemigos, sino también de odiar a sus amigos."

Simplified Meaning:

A knowledgeable person needs to be able to care about those who are against them, and also be ready to criticize or oppose those who are close to them. This means that sometimes even friends can do wrong things, and it's important to recognize and address those wrongs, rather than letting friendship blind you. For example, if your friend is being unfair to someone else, a truly wise person would speak up against that, even if it means creating tension with their friend. Similarly, it's helpful to understand and learn from your enemies, which might reduce hatred and lead to better solutions. So, the advice here is to not let emotions cloud your judgment and be fair no matter who is involved. This teaches us to stand up for what's right and be honest, regardless of our personal feelings towards the people involved.