During the final years of the Western Han Dynasty, a Confucian scholar named Xue Fang, styled Zirong, from the Qi region (modern-day Shandong area), was renowned for his mastery of classical texts, meticulous conduct, noble character, and literary talent, authoring dozens of widely circulated poems and rhapsodies that earned him great fame.
Xue Fang was a man of great renown, but he despised the corruption and darkness of officialdom, preferring to live in seclusion teaching and writing rather than serve as an official. Once, a libationer (an academic official) summoned him to office, but Xue Fang declined. Later, when Wang Mang usurped the throne and proclaimed the "Xin" dynasty, he too heard of Xue Fang's fame and prepared a carriage to bring him to the capital for an official post. Through the envoy, Xue Fang politely refused Wang Mang, saying, "In the days of Yao and Shun, there were recluses like Chao Fu and Xu You. Now that a wise ruler seeks to revive their sage virtue, I intend to uphold the same hermit's integrity as those who lived on Mount Ji."
When Wang Mang heard this, he was delighted that Xue Fang had compared him to the legendary sage-kings Yao and Shun, and so he did not force Xue Fang to take an official post.
Mount Ji is said to be where the recluses Chao Fu and Xu You of Yao and Shun's time lived in seclusion. The idiom "Ji Mountain Integrity" refers to the moral integrity of those like Xu You and Chao Fu who lived in seclusion on Mount Ji.
Source: *Book of Han*, Chapter "Biography of Bao Xuan"
Meaning of the Idiom: Later, the Chinese idiom "箕山之节" came to describe Ji Mountain Integrity refers to the moral integrity of those like Xu You and Chao Fu who lived in seclusion on Mount Ji.