《元史·列传·卷二十五》
后来伯颜又擅贬宣让、威顺二王，顺帝非常忿恨，决心撤伯颜之职，把这打算告诉了脱脱，脱脱回去向老师吴直方请教，直方说： 此事关系到社稷安危，必须严格保密。 
帝曰： 此皆朕意，非脱脱罪也。 及伯颜擅贬宣让、威顺二王，帝不胜其忿，决意逐之。一日，泣语脱脱，脱脱亦泣下，归与直方谋。直方曰： 此宗社安危所系，不可不密。
Later, Boyan also arbitrarily demoted the Kings of Xuanrang and Weishun. Shun Emperor was very angry and determined to dismiss Boyan from his position. He told Toghto about his plan, and Toghto went back to ask his tutor Wu Zhifang for advice. Wu Zhifang said: This matter is related to the safety of the country. It must be strictly confidential.