《论衡·卷十六·讲瑞篇》
从子贡知道孔子是圣人，三年才能确定这件事上看，俗儒没有子贡的才能，他们见到圣人，不跟他学习，凭仓猝之间的观察，又没有三年的接触，自称知道了圣人，是完全错了！
以子贡知孔子，三年乃定。世儒无子贡之才，其见圣人不从之学，任仓卒之视，无三年之接，自谓知圣，误矣！
From the fact that Zilu, after he knew Confucius was a sage, took three years to confirm this fact, we can see that ordinary scholars do not have Zilu's talent; when they meet a sage, they do not learn from him. Based on a cursory observation and without having contact with him for three years, they claim to have known the sage, which is totally wrong.