Whenever we start to talk about tatbir, the people try to refute us saying when did any Imam (AS) tell us to do this or when did they do it themselves. Is there anyone who was more agrieved then Imam Sajjad (AS) they ask? Sometimes they say that it is mentioned in The Quran that we are not allowed to hurt our body. If you can please tell me how to refute there argument, it will be highly appreciated.

The harms that are haram in Islam are the harms that do three things: 1- Kill the human being instantly 2- Stop a body limb from working 3- Stop a human power (such as producing children) This is according to the Fiqh of Imam al Sadiq (a.s). Any other harm is not considered Haram, such as fast-food, smoking, speeding in your vehicle, etc.