以售其奸 To sell one's evil deeds
Explanation
指为了达到某种目的，不择手段，暗中进行欺骗、阴谋活动。
Refers to unscrupulous means to achieve a certain goal, secretly carrying out deception and conspiracy.
Origin Story
战国时期，魏国有个叫庞涓的人，他自幼与孙膑一起学习兵法，后来庞涓先入仕，为了打压孙膑，设计陷害，使孙膑遭受膑刑。孙膑忍辱负重，后被齐国将军田忌赏识，为齐国出谋划策，在桂陵之战和马陵之战中两次大败庞涓，最终使庞涓自刎而死。庞涓为了达到自己飞黄腾达的目的，不择手段，以售其奸，最终却害人害己，落得个身败名裂的下场。这真是应了那句话：害人终害己。
During the Warring States period, there was a man named Pang Juan in the Wei kingdom. He and Sun Bin studied military strategy since childhood. Later, Pang Juan entered government service first. In order to suppress Sun Bin, he schemed to frame him, causing Sun Bin to suffer the punishment of having his kneecaps broken. Sun Bin endured the humiliation and injustice until he was discovered by Tian Ji, a general from the Qi kingdom, who appointed him as an advisor. Sun Bin helped Qi win two crucial battles and ultimately led to Pang Juan's suicide. To further his own career, Pang Juan employed unethical means and attempted to betray and harm Sun Bin to achieve his goals. In the end, however, he harmed himself and became infamous. This illustrates the old saying: Those who harm others ultimately harm themselves.
Usage
多用于贬义，形容人为了达到目的不择手段，阴险狡诈。
Mostly used in a derogatory sense, describing someone who will stop at nothing to achieve their goals, cunning and deceitful.
Examples
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他总是以权谋私，以售其奸。
tā zǒngshì yǐ quán móu sī，yǐ shòu qí jiān
He always abuses his power for personal gain, scheming to sell his evil deeds.
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为了达到目的，他不惜以售其奸，陷害他人。
wèile dádào mùdì，tā bù xī yǐ shòu qí jiān，xiàn hài tārén
To achieve his goals, he does not hesitate to betray and harm others to achieve his own goals