﴿ لَّوْلَا جَآءُو عَلَيْهِ بِأَرْبَعَةِ شُهَدَآءَ ۚ فَإِذْ لَمْ يَأْتُوا۟ بِٱلشُّهَدَآءِ فَأُو۟لَٰٓئِكَ عِندَ ٱللَّهِ هُمُ ٱلْكَٰذِبُونَ ﴾

“why do they not [demand of the accusers that they] their allegation? for, if they do not produce such wit­nesses, it is those [accusers] who, in the sight of God, are liars indeed!”

Every right-minded believer must think well of his fellow believer. Entertaining bad opinions about others is actually exposing one’s own evil nature and, conversely, holding a good opinion about others is a proof of one’s own righteous nature. The correct procedure is that whenever anyone speaks ill of any other person, proof should immediately be demanded of him. One who hears such an allegation should not simply start repeating it to others. On the contrary, he should ask the informer to furnish evidence according to the Islamic law to prove that he is right. What he has to say may be worth considering only if he produces witnesses, otherwise he himself becomes the guilty person. Nobody has the right to hold anyone guilty without proof.