During the reign of Emperor Xuan of the Western Han Dynasty, Zhang Chang served as the chief of Chang'an's metropolitan region for nine years, maintaining order across twelve counties with such skill that the capital remained peaceful.
Later, he was impeached for his involvement in the case of Colonel Yang Yun. Though he had not yet been dismissed, his subordinates all knew his days in office were numbered.
Zhang Chang, however, did not stop handling affairs just because he was about to be dismissed. One day, he ordered his subordinate officer Xu Shun to investigate a case. Xu Shun, believing Zhang Chang would soon be removed from office, pretended to agree but instead went home to sleep, neglecting the investigation.
Someone advised Xu Shun not to act this way, but Xu Shun replied, "I have handled countless cases for Zhang Chang. Now he will only serve as the capital's governor for five more days. Why should I still exert myself for him?"
Upon learning of this, Zhang Chang immediately ordered Xu Shun arrested and, on charges of dereliction of duty, sentenced him to death, carrying out the execution without delay.
Xu Shun's family filed an appeal, accusing Zhang Chang of killing an innocent man without cause
After some time, the new capital governor, unfamiliar with local conditions and lax in enforcing the law, allowed the city's public order to deteriorate with constant incidents. Emperor Xuan of Han, recalling Zhang Chang's experience in governing the capital and his strict enforcement of the law, summoned him back and reappointed him as the capital governor.
Later, the idiom "Five Days as Capital Governor" came to describe a very short tenure or someone about to leave office.
Source: *Book of Han*, "Biography of Zhang Chang"
Meaning of the Idiom: Later, the Chinese idiom "五日京兆" came to describe a very short tenure or someone about to leave office.