《礼记·檀弓上》
如果为国君谋划如何保卫国都，不幸国都处于危险之中，就应引咎接受放逐，让开贤路。 
公叔文子升于瑕丘，蘧伯玉从。
If he plans for the monarch to defend the capital, and unfortunately the capital is in danger, he should blame himself and accept exile to make way for a worthy man.