《淮南子·道应训》
子韦说： 你讲的做君主的三条原则，所以上天也必有 三 赏，荧惑星移动三舍，每移动一舍就经过七个星座，三七二十一，所以君王能延长寿命二十一年。我愿爬伏在陛阶下等候着，如果荧惑星呆在原处不移徙，我情愿替君王去死！ 景公说： 可以。 
对曰： 君有君人之言三，故有三赏，星必三徙舍，舍行七里，三七二十一，故君移年二十一岁，臣请伏于陛下以伺之，星不徙，臣请死之。 公曰： 可。 
Ziwu said: You have said three principles of being a monarch, so the heavens will definitely have three rewards, Venus will move three houses, and each house will pass through seven constellations, three seven and twenty-one, so the monarch can prolong his life by twenty-one years. I am willing to crawl under the steps and wait. If the venus stay in the same place and do not move, I am willing to die for the monarch! Duke Jing said: Yes.