I would like to share one. Yangzhen was born in a noted family in the Han Dynasty. He was a good official and never accept gifts, bribe in the other way. He once recommended an person called Wang Mi to be an official. One year, Yangzhen was on his way to another place, being the local official. He passed the district that governed by Wang Mi. Wang Mi want to express his gratitude and ask someone bring 10 jin (5kg) gold as gift to Yang Zhen at night, but was denied. Yang Zhen later asked Yang Mi why he did this. Wang answered no one would know this if I give it at night. Yang replied: Is this the way you understand your old friend and his personality? The god knows, the heaven knows, you know and I know. How could you say no one knows. Wang felt ashamed and went away. That's all. I guess Yang Zhen would never think this thing could happed when he recommended Wang Mi.