◎ 家贼难防 jiāzéi-nánfáng
[thief in the family is difficult to detect; a thief from within is hard to guard against;it is difficult to forestall a thief within the house] 家属或内部的人作弊营私难以防范
【解释】家里人作贼难以防范。比喻隐藏在内部的坏人不容易防范。
【出处】宋·释普济《五灯会元》卷三十七：“问：‘家贼难防时如何？’师曰：‘识得不为冤。’”
【语法】主谓式；作谓语、宾语；比喻内部的坏人最难防范