In The Nichomachean Ethics Aristotle often mentions beating one's own father. So does Socrates in Plato's Euthyphro. I was just wondering why would they use such examples, I'm guessing it must be based on something.
I'm not terribly familiar with these texts, but my guess is that it is being used as a symbol of the inversion of proper social norms. In Aristophanes' Clouds, the son who is taught the ways of Sokrates ends up abusing his father, which is a demonstration of just how much the teachings of philosophy and the reasoning of the Bad Argument have corrupted him. In a society like Classical Athens, little could be more outrageous and morally wrong than displaying hubris (aggressive arrogance) towards your own father.