During the reign of Emperor Jing of the Western Han Dynasty, the upright politician Jia Yi observed a group of arrogant courtiers bullying others around the emperor. Everyone feared indirectly offending the emperor, so no one dared to challenge them.
So Jia Yi devised a plan. One day, after meeting with Emperor Jing, he deliberately said to the emperor:
"Your Majesty, have you heard the saying 'spare the rat to save the dish'?" "No. What does that mean?" asked Emperor Jing.
Jia Yi replied calmly, "There was a mouse that came out of its hole in the dead of night to steal food, but was discovered by the owner. The mouse fled to hide beside a large rice jar. The owner wanted to hit the mouse but was afraid of breaking the jar, and for a moment didn't know what to do."
Emperor Jing nodded and said, "It's truly difficult to hit the rat without breaking the rice jar."
Jia Yi continued, "By the same logic, many of your close ministers commit errors, yet no one dares to criticize them. Because they are always by your side, to avoid offending you, everyone can only harbor silent anger without speaking out."
Emperor Jingdi suddenly realized the truth: Jia Yi was subtly warning him not to shield his favored ministers from their mistakes.
Later, the idiom "sparing the rat for fear of breaking the vase" came to mean hesitating to act for fear of harming an innocent third party.
Source: *Jia Yi (Western Han Dynasty), "Strategies for Governance"*
Meaning of the Idiom: Later, the Chinese idiom "投鼠忌器" came to describe hesitating to act for fear of harming an innocent third party.