Xu Shu (simplified: 徐庶, traditional: 徐庶, pinyin: Xú Shù), courtesy name Yuanzhi (元直), was from Yingchuan and had studied with Sima Hui in Jing Province. He served Liu Bei briefly and recommended Zhuge Liang, saying that Liu Bei must seek him in person and that Zhuge Liang could not be summoned. Before leaving Liu Bei’s service, Xu Shu pointed him toward the “Crouching Dragon” (卧龙). According to the Romance of the Three Kingdoms and some historical accounts, Xu Shu’s mother was captured by Cao Cao (or Cao had a letter forged in her name summoning Xu Shu); Xu Shu left for Cao’s camp to save her. He reportedly swore never to give Cao Cao strategic advice—“not one word” (一言不獻)—and in Wei he held office (e.g. Right General of the Army, Director of the Secretariat) but did not offer counsel. His recommendation of Zhuge Liang was crucial to Liu Bei’s later success.
Xu Shu 徐庶 Yuanzhi 元直
Adviser to Liu Bei who recommended Zhuge Liang as 'Crouching Dragon'; left for Cao Cao after his mother was captured (or a forged letter); swore not to give Cao Cao strategy; served Wei in office but did not advise.