Sahih Muslim 2606
Sahih Muslim · Book 45: The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship · The Prohibition Of Malicious Gossip (Namimah)
'Abdullah b. Mas'ud reported that Muhammad (ﷺ) said:
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى ، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ ، حَدَّثَنَا شُعْبَةُ ، سَمِعْتُ أَبَا إِسْحَاقَ ، يُحَدِّثُ عَنْ أَبِي الأَحْوَصِ ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ ، قَالَ إِنَّ مُحَمَّدًا صلى الله عليه وسلم قَالَ " أَلاَ أُنَبِّئُكُمْ مَا الْعَضْهُ هِيَ النَّمِيمَةُ الْقَالَةُ بَيْنَ النَّاسِ " . وَإِنَّ مُحَمَّدًا صلى الله عليه وسلم قَالَ " إِنَّ الرَّجُلَ يَصْدُقُ حَتَّى يُكْتَبَ صِدِّيقًا وَيَكْذِبُ حَتَّى يُكْتَبَ كَذَّابًا " .
Should I inform you that slandering, that is in fact a tale-carrying which creates dissension amongst people, (and) he (further) said: The person tells the truth until he is recorded as truthful, and lie tells a lie until lie is recorded as a liar.