But if the sinning is definite then it is obligatory for you...

But if the sinning is definite then it is obligatory for you to address yourself from the viewpoint of “Nahy Anil Munkar” (stopping evil). Make a decision to make him give up this sin. Do not stand up and begin to degrade and disgrace others. For example, you say: I have seen him walking behind a woman. May be she was his wife. You do not know him. She may be his mother or sister.

Even if you are sure that she was a stranger lady, it is obligatory for you to tell him: What is this deed that you did? And not that you may disgrace him. Yes, I saw him…