Sahih Muslim
Book 45: The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship
كتاب البر والصلة والآداب
217 hadith in this book
Abu Huraira reported Allah's Messenger (ﷺ) as saying: Do you know what is backbiting? They (the Companions) said: Allah and His Messenger know best. Thereupon he (the Holy Prophet) said: Backbiting implies your talking about your brother in a manner which he does not like. It was said to him: What is your opinion about this that if I actually find (that failing) in my brother which I made a mention of? He said: If (that failing) is actually found (in him) what you assert, you in fact backbited him, and if that is not in him it is a slander.
حَدَّثَنَا يَحْيَى بْنُ أَيُّوبَ، وَقُتَيْبَةُ، وَابْنُ، حُجْرٍ قَالُوا حَدَّثَنَا إِسْمَاعِيلُ، عَنِ الْعَلاَءِ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَتَدْرُونَ مَا الْغِيبَةُ " . قَالُوا اللَّهُ وَرَسُولُهُ أَعْلَمُ . قَالَ " ذِكْرُكَ أَخَاكَ بِمَا يَكْرَهُ " . قِيلَ أَفَرَأَيْتَ إِنْ كَانَ فِي أَخِي مَا أَقُولُ قَالَ " إِنْ كَانَ فِيهِ مَا تَقُولُ فَقَدِ اغْتَبْتَهُ وَإِنْ لَمْ يَكُنْ فِيهِ فَقَدْ بَهَتَّهُ " .
Hadith text, translations and grading are courtesy of Sunnah.com.