Ji Bu, a native of the Chu state during the Warring States period, served as an imperial advisor and later as the governor of Hedong Commandery in the early Han Dynasty. Known for his unwavering sense of justice, he championed the oppressed against the powerful and spoke bluntly at court, earning widespread renown.
In the state of Chu lived a wealthy man named Caoqiu Sheng, who used his fortune to befriend powerful figures like Dou Changjun, hoping to boost his own reputation. When Ji Bu heard of this, he wrote to Dou Changjun, warning, "Caoqiu Sheng is not a man of virtue—you should avoid him." Soon after, Caoqiu Sheng sought an introduction to Ji Bu and begged Dou Changjun for a letter of recommendation. Though Dou Changjun knew Ji Bu despised the man, he eventually relented under Caoqiu Sheng's persistent pleas and wrote the letter.
Cao Qiusheng first sent a letter ahead to Ji Bu. Furious, Ji Bu waited at home, ready to thoroughly humiliate him.
Cao Qiusheng arrived at Ji Bu's home, bowed with clasped hands, and flattered him, saying, "People of Chu all say, 'A hundred catties of gold are not worth one promise from Ji Bu.' How have you gained such a fine reputation throughout Chu and Liang? I am from Chu, and you are also from Chu. If I associate with you, I can make your name known throughout the world. So why do you reject me?"
Ji Bu was delighted by Cao Qiusheng's words, treating him as an honored guest and hosting him for months, even sending him off with generous gifts.
Thanks to Cao Qiusheng's efforts, Ji Bu's reputation grew even more illustrious.
Later, the idiom "Ji Bu's Promise" came to describe someone who is extremely trustworthy in keeping their word.
Source: *Records of the Grand Historian*, "Biographies of Ji Bu and Luan Bu"
Meaning of the Idiom: Later, the Chinese idiom "季布一诺" came to describe how someone is extremely trustworthy in keeping their word.