The man who does evil to another does evil to himself, and the evil counsel is most evil for him who counsels it.
HesiodSo the people will pay the penalty for their kings' presumption, who, by devising evil, turn justice from her path with tortuous speech.
HesiodThe best man of all is he who knows everything himself. Good also the man who accepts another's sound advice; but the man who neither knows himself nor takes to hear what another says, he is no good at all.
Hesiod