《孔子家语·正论解》
昭子当政后，召集他的臣仆说： 竖牛祸害叔孙氏，使祸乱一个接着一个，杀害嫡子拥立庶子，又把边邑的地方用来行贿，以求免去罪行，没有比他的罪行再大的了，必须迅速把他杀掉。 
昭子既立，朝其家众曰： 竖牛祸叔孙氏，使乱大从，杀适立庶，又披其邑，以求舍罪。罪莫大焉！必速杀之。 
After Zhaozi took control of the state, he summoned his ministers and said: The abominable Niu has caused one disaster after another for the Shusun family. He killed the heir apparent and installed his younger son as heir; he used the border town to bribe others in order to avoid punishment. There is no greater crime than his, and we must kill him immediately.