يَا أَيُّهَا الَّذِينَ آمَنُوا اجْتَنِبُوا كَثِيرًا مِّنَ الظَّنِّ إِنَّ بَعْضَ الظَّنِّ إِثْمٌ وَلَا تَجَسَّسُوا وَلَا يَغْتَب بَّعْضُكُم بَعْضًا...

If a man harbours suspicion against another, everything about the latter appears wrong to him, for his mind starts drifting in negative and wrong directions. He starts searching for his shortcomings rather than his good points. It becomes his favourite ploy to describe his weaknesses and then to denigrate him. The root of many social evils is unfounded suspicion. It is therefore necessary for man to be alert to this. He should not allow such suspicion to enter his mind. If you are suspicious of someone, you can always meet him and talk frankly to him. But, it would be highly unethical to speak ill of a person, if he was not there to defend himself. An individual may occasionally make such mistakes. But, if he is God-fearing, he will not persist in doing so. His fear of God will warn him about his mistake and consequently he will give up his wrong approach and seek God’s pardon.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (49:12)