《新唐书·列传·卷九十九》
杨嗣复说 ：我听说左边和右边的佩剑，互相嘲笑，不知郑覃到底说谁拉宗派呢？ 
嗣复曰： 臣闻左右佩剑，彼此相笑，未知覃果谓谁为朋党邪？ 
Yang Sif said: I heard that the people with swords on the left and right ridiculed each other. I wonder who Zheng Tan is referring to when he says someone is forming factions. 