《史记·三十世家·赵世家》
我听说，奸臣在朝廷是国家的祸害；谗臣在宫中是君主的蛀虫。
吾闻之也，奸臣在朝，国之残也；谗臣在中，主之蠹也。
I have heard that treacherous ministers are the country's misfortune when they are at court; that flatterers are a monarch's canker when they are in the palace.