以儆效尤 to make an example of
Explanation
儆：使人警醒，不犯错误；效：仿效，效法；尤：过失。指处理一个坏人或一件坏事，用来警告那些学着做坏事的人。
Jǐng: to alert sb. to avoid mistakes; xiào: to imitate, emulate; yóu: fault. Refers to handling a bad person or a bad thing to warn those who are learning to do bad things.
Origin Story
话说唐朝时期，京城长安有一伙地痞流氓，经常欺压百姓，无恶不作。百姓敢怒不敢言，苦不堪言。长安知府李大人得知此事后，勃然大怒，下令彻查此事。经过一番努力，李大人终于抓到了这伙地痞的为首者——张三。张三罪行累累，证据确凿，李大人决定将其公开处决，以儆效尤。张三被押赴刑场，行刑前，李大人当着所有百姓的面，厉声说道："张三罪大恶极，罪不容诛！今日将其正法，以儆效尤！希望各位引以为戒，不要再犯类似的错误！"张三被处决后，长安城再也没有出现过类似的恶性事件。百姓们安居乐业，过上了平静的日子。
During the Tang Dynasty, a gang of thugs and hooligans in the capital Chang'an frequently oppressed the people and committed all kinds of evil deeds. The people dared not speak out, and they suffered greatly. When Magistrate Li of Chang'an learned of this, he became furious and ordered a thorough investigation. After much effort, Magistrate Li finally caught the leader of the gang, Zhang San. Zhang San had committed numerous crimes, and the evidence was conclusive, so Magistrate Li decided to publicly execute him to deter others. Zhang San was taken to the execution ground. Before the execution, Magistrate Li said loudly in front of all the people, "Zhang San has committed heinous crimes, his crimes cannot go unpunished! Today, he will be executed to serve as a warning to others! I hope that everyone will take this as a warning and not commit similar mistakes again!" After Zhang San was executed, no similar evil incidents occurred in Chang'an. The people lived and worked in peace and led peaceful lives.
Usage
用于处理违法犯罪行为，以警示他人。
Used to deal with illegal and criminal acts to warn others.
Examples
-
公司处理了一起贪污案，以儆效尤。
gōngsī chǔlǐ le yī qǐ tānwū àn, yǐ jǐng xiào yóu
The company handled a case of embezzlement as a warning to others.
-
为了维护社会治安，必须严惩犯罪分子，以儆效尤。
wèile wéihù shèhuì zhì'ān, bìxū yánchéng fànzuì fènzǐ, yǐ jǐng xiào yóu
To maintain public order, criminals must be severely punished to deter others..