Page "Xun Yu" Paragraph 9

Knowing that Dong Zhao was probably a conduit for Cao Cao, when approached by the former for his support, Xun Yu told Dong that Cao's personal mission was one of restoring the Han Dynasty and would not approve of such a move — thus possibly hinting to Cao that he should abandon the idea.

According to volume 10 of Chen Shou's Records of Three Kingdoms, Xun Yu's remarks were said to have greatly displeased Cao Cao.