There is a person who never talks about others. He is worse than others! What should I say to make him speechless? He belongs to the kind of person in pot calling the kettle black.

If you want to shut him up, you can slap him in the mouth. I have also met people who exaggerate the facts and say that they are incompetent and that others are not good. If killing people is not illegal, he will become minced meat. The best way is to ignore him. He won't say a word, okay? Then he stinks at him.