Professor Ansarain said: the commander of the faithful, Imam Ali (AS) has written a letter to Mohammad Hanifi that is in the 11th volume of "Walesa al-Shia" book. Imam Ali says in this letter: don’t say what you are not certain about, but in the society the people do vice a versa, Imam Ali further adds: not only you need to avoid saying what you are not sure about but you have to avoid spreading people’s sins even if you are certain about them.
the commander of the faithful says as well as the holy Quran in the Surah al-Nour: you don’t have the right to spread somebody’s sins among your family, relatives and people,
“إِنَّ الَّذِينَ يُحِبُّونَ أَنْ تَشِيعَ الْفَاحِشَةُ فِي الَّذِينَ آمَنُوا لَهُمْ عَذَابٌ أَلِيمٌ فِي الدُّنْيَا وَالْآخِرَةِ وَاللَّهُ يَعْلَمُ وَأَنْتُمْ لَا تَعْلَمُونَ”
Those who like to publicize indecency among the believers will face painful torment in this world and in the life to come. God knows what you do not know. (Surah al-Nour-19)
The sinner will repent and he is forgiven, but you who have spread the sin must go to hell, while you have not enjoyed the pleasure of sin.
source : erfan.ir