《史记·七十列传·乐毅列传》
我听说古代的君子，在与人断绝交往时不说别人的坏话；忠良的臣子离开原来的国家，不洗雪自己的罪过和冤屈。
臣闻古之君子，交绝不出恶声；忠臣去国，不絜其名。
I heard that the gentlemen of the ancients did not speak ill of others when they broke off with people; and that the loyal ministers did not wash away their crimes and grievances when they left their original country.