无情无义 Ruthless and unprincipled
Explanation
形容一个人没有一点情义，很冷酷，对人很无情。
Describes a person who has no loyalty or compassion, is very ruthless, and is unfeeling towards others.
Origin Story
传说在战国时代，有一位名叫伍子胥的将军，因遭奸臣陷害，被迫逃亡到吴国。他投靠了吴王光，并辅佐吴王光打败了楚国，为吴国建立了功勋。但吴王光后来却猜忌伍子胥，派人将他杀了。伍子胥临死前对吴王说：“我死后，请把我眼睛挖出来，悬挂在城墙上，我要看着楚国灭亡！”吴王答应了，伍子胥死后，他的眼睛被挖出来，悬挂在吴国城墙上。后来，吴国果然被楚国灭亡了。伍子胥的眼睛，见证了吴国的兴衰，也见证了世态的无情。
Legend has it that during the Warring States period, there was a general named Wu Zixu who was forced to flee to the Kingdom of Wu after being framed by a treacherous minister. He sought refuge with King Guang of Wu and helped him defeat the Kingdom of Chu, earning great merit. But later, King Guang of Wu became suspicious of Wu Zixu and had him killed. Before his death, Wu Zixu said to King Guang: “When I die, please dig out my eyes and hang them on the city wall. I want to see Chu destroyed with my own eyes!” King Guang agreed and after Wu Zixu died, his eyes were dug out and hung on the city wall of Wu. Eventually, Wu was indeed destroyed by the Kingdom of Chu. Wu Zixu's eyes witnessed the rise and fall of Wu and testify to the ruthlessness of the world.
Usage
形容一个人缺乏感情，没有情义，冷酷无情。
Describes a person who lacks feelings and loyalty, is cold and ruthless.
Examples
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他为了自己的利益，对朋友都如此无情无义，让人失望。
tā wèile zìjǐ de lìyì, duì péngyou dōu rúcǐ wú qíng wú yì, ràng rén shīwàng.
He was so ruthless and unprincipled to his friends for his own interests, it's disappointing.
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他对朋友的背叛，真是无情无义，令人寒心。
tā duì péngyou de bèipàn, zhēnshi wú qíng wú yì, lìng rén hánxīn
His betrayal of his friends was so ruthless and unprincipled that it makes people shudder.