The Republic by Plato Part 1 Page 25

Then to them the good will be enemies and the evil will be their friends? True.

And in that case they will be right in doing good to the evil and evil to the good?

Clearly.

But the good are just and would not do an injustice?

True.

Then according to your argument it is just to injure those who do no wrong?

Nay, Socrates; the doctrine is immoral.

Then I suppose that we ought to do good to the just and harm to the unjust?

I like that better.

But see the consequence: — Many a man who is ignorant of human nature has friends who are bad friends,