《宋史·列传·卷一百八十六》
一天傍晚，程颢、程颐二兄弟来了，与他讨论《易》经，第二天告诉别人说： 近来见到二程，研究了解《易》中道义很高深，是我所达不到的，你们可拜他为老师。 于是撤掉师座，停止讲学。
一夕，二程至，与论《易》，次日语人曰： 比见二程，深明《易》道，吾所弗及，汝辈可师之。 撤坐辍讲。
One evening, the two Cheng brothers, Hao and Yi, came to discuss the Book of Changes with him; the following day, he told others: "Recently, I have met the two Chengs and have discussed the profound principles in the Book of Changes; they are beyond my reach; you all can study with them." Therefore, he suspended his teachings and dismissed his students.