KohR[1]26:2(22) :טפשא סבר דכל עמא טפשין כותיה והוא לא ידע דהוא טפשא וכל עמא חכים‏ : the fool thinks that all people are fools like him, while he does not know that he is a fool, but all people are wise.
See the entire entry for ṭp̄eš, tap̄šā adj. stupid, foolish