《资治通鉴·唐纪·唐纪五十四》
有一次，吕元膺在夜间要登城，城门已经上锁，守护城门的人不肯为他打开城门。
元膺尝欲夜登城，门已锁，守者不为开。
One time, Lu Yanyuan wanted to climb the city wall at night, but the city gate was already locked and the guards refused to open it for him.