He harms himself who does harm to another, and the evil plan is most harmful to the planner.
Of themselves diseases come upon men continually by day and by night, bringing mischief to mortals silently; for wise Zeus took away speech from them. So is there no way to escape the will of Zeus
Do not seek evil gains; evil gains are the equivalent of disaster
Do not let a flattering woman coax and wheedle you and deceive you; she is after your barn.
You trust a thief when you trust a woman.
Neither make thy friend equal to a brother; but if thou shalt have made him so, be not the first to do him wrong.