Xu Xianfei can be said to be the teacher of Wu Zetian. Wu Meiniang was not loved when he entered the palace, but Xu Xianfei could stand the love of Emperor Taizong for decades, so Wu Meiniang asked her for advice. She said the famous sentence, "Be a gentleman with color, be short"; Those who serve the king with talent are also long.
? Tang Taizong is a person who likes others to make outspoken suggestions. Therefore, Xu Xianfei often expressed his ideas to Emperor Taizong. By the end of Zhenguan, Emperor Taizong had slackened his treatment. He built a palace in his later years and sent troops to attack Korea. Knowing the sufferings of the people, Xu Xianfei advised Li Shimin to let the people recuperate. He wrote "Advise Taizong to stop fighting, stop fighting" to persuade Li Shimin. This article is well-founded and rich in vocabulary.
The purpose of exhorting Emperor Taizong to stop fighting was to criticize his fault, but the wording was euphemistic and tortuous, the metaphor was vivid and the language was sincere, which sounded the alarm for the increasingly arrogant Emperor Taizong. Emperor Taizong also appreciated Xu Hui's literary talent and could afford a virtuous word.
After Li Shimin's death, Xu Xianfei died of grief and depression. After his death, he was buried in Li Shimin's mausoleum, which was considered satisfactory.