睚眦必报 to bear a grudge over trifles
Explanation
睚眦必报，指对再小的怨恨也要报复，形容心胸狭窄，不能容人。
Yázì bì bào means to retaliate even for the smallest resentment, describing a narrow-minded and intolerant personality.
Origin Story
战国时期，范雎为魏国大夫须贾出使齐国，回国后须贾向魏齐诬告范雎通敌，范雎被打得半死，逃到秦国。后来范雎成为秦国宰相，须贾出使秦国，范雎故意装作穷人，须贾见他可怜，送他一件衣服。范雎揭示身份后，须贾惊恐万分，连连谢罪。范雎说：‘一饭之德必偿，睚眦之怨必报’。最终，范雎还是没有放过须贾，让他尝尽了苦头。这个故事说明了睚眦必报的恶劣后果，告诫人们要宽容待人，切勿心胸狭窄。
During the Warring States period, Fan Ju served as an official of the state of Wei and was falsely accused by his colleague Xu Jia of conspiring with the enemy state. Fan Ju was severely injured and fled to Qin. Later, Fan Ju became the prime minister of Qin. When Xu Jia visited Qin, Fan Ju pretended to be poor and destitute. Xu Jia felt sorry for him and gave him a piece of clothing. When Fan Ju revealed his true identity, Xu Jia was very frightened and repeatedly apologized. Fan Ju said: "I will repay even the smallest kindness and avenge even the smallest grievance." In the end, Fan Ju did not let Xu Jia go unpunished and made him suffer the consequences of his actions. This story shows the bad consequences of vengefulness and warns people to be tolerant and not petty.
Usage
形容心胸狭窄，不能容人。常用于贬义。
Describes a narrow-minded and intolerant personality. Often used in a derogatory sense.
Examples
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他是一个睚眦必报的人，谁要是得罪了他，他一定会想方设法地报复。
tā shì yīgè yázì bì bào de rén, shuí yào shì dǎo le tā, tā yīdìng huì xiǎng fāngfǎ de bàofù。
He is a person who will repay any slight, whoever offends him, he will find ways to retaliate.
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职场竞争激烈，但我们不能睚眦必报，要保持宽容的心态。
zhí chǎng jìngzhēng jīliè, dàn wǒmen bù néng yázì bì bào, yào bǎochí kuānróng de xīntài。
Workplace competition is fierce, but we cannot be petty and should maintain a tolerant attitude.
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生活中难免会遇到一些不愉快的事情，但是我们应该学会放下，不要睚眦必报。
shēnghuó zhōng nánmiǎn huì yùdào yīxiē bù yúkuài de shìqíng, dànshì wǒmen yīnggāi xuéhuì fàngxià, bù yào yázì bì bào。
In life, we inevitably encounter unpleasant things, but we should learn to let go and not be spiteful and retaliate at every little thing..