《韩非子·难二》
现在他像信任管仲那样使用竖刁、易牙，以致死后蛆虫爬出门外还不能安葬。桓公不能识别臣子欺主还是不欺主，已是很明白的了，而他任用臣子又是那样专一，所以说：桓公是昏庸糊涂的君主。
然虽知不欺主之臣，今桓公以任管仲之专借竖刁、易牙，虫流出尸而不葬，桓公不知臣欺主与不欺主已明矣，而任臣如彼其专也，故曰：桓公暗主。
Now he treated Shu Diao and Yi Ya with the same trust he placed in Guan Zhong, so that after his death, maggots crawled out of his gate, and his body still could not be buried. It was clear that Duke Huan could not distinguish between ministers who betrayed their monarch and those who did not, and yet he was so devoted to them. Therefore, it may be said that Duke Huan was a muddle-headed monarch.