Records of the Three Kingdoms
Jia Xu, courtesy name Wenhe, was from Guzang in Wuwei. Yan Zhong once said he had the unexpected turns of Zhang Liang and Chen Ping. After Dong Zhuo’s death, Li Jue and Guo Si meant to disband and flee to Liangzhou. Jia Xu told them to gather the army, attack Chang’an, and avenge Dong Zhuo. Chang’an fell again and Wang Yun was killed. That advice is the act most held against him.
He then planned for Zhang Xiu. In 197 Zhang Xiu surrendered at Wan and rebelled. Cao Cao’s eldest son Cao Ang, his nephew Cao Anmin, and the captain Dian Wei died in that fight. Jia Xu stopped Zhang Xiu from pursuing the retreating Cao Cao too far, and when Cao Cao returned he urged surrender. In 199 Zhang Xiu followed that advice. Cao Cao did not pursue the grudge of Wan and joined the families by marriage.
Before Guandu, Yuan Shao tried to recruit Zhang Xiu. Jia Xu refused in front of the envoy and argued that Yuan Shao could not abide men of talent while Cao Cao could use people past a private injury. After joining Cao he rarely advertised his plans. When Cao Cao asked whether to name Cao Pi or Cao Zhi, Jia Xu did not answer directly. He said he was thinking of Yuan Shao and Liu Biao, who had set aside the elder son. Cao Cao laughed and understood. Jia Xu died of illness in 223, at seventy-seven. Chen Shou places him with Xun You and says his calculations left little out, and also that his conduct in the Li Jue years failed a moral measure.
Romance of the Three Kingdoms
The novel calls him the poisonous counselor. Li Jue and Guo Si’s attack on Chang’an, and the defeat at Wan — Cao Cao cutting his beard and dropping his robe, Dian Wei’s death — are laid to his planning. When he talks Zhang Xiu into joining Cao, he sets the interests out one by one.
The silence over the heir is a very short conversation. In the later Wei chapters he almost stops offering schemes, which matches the histories’ picture of a man who kept his gate shut.
Reference: Wikipedia · Jia Xu