Sahih al-Bukhari 6131
Narrated Aisha:
A man asked permission to see the Prophet. He said, "Let Him come in; What an evil man of the tribe 
he is! (Or, What an evil brother of the tribe he is). 
But when he entered, the Prophet (ﷺ) spoke to him gently in a polite manner. I said to him, "O Allah's 
Apostle! You have said what you have said, then you spoke to him in a very gentle and polite manner? 
The Prophet (ﷺ) said, "The worse people, in the sight of Allah are those whom the people leave 
(undisturbed) to save themselves from their dirty language."
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا سُفْيَانُ، عَنِ ابْنِ الْمُنْكَدِرِ، حَدَّثَهُ عُرْوَةُ بْنُ الزُّبَيْرِ، أَنَّ عَائِشَةَ، أَخْبَرَتْهُ‏.‏ أَنَّهُ، اسْتَأْذَنَ عَلَى النَّبِيِّ صلى الله عليه وسلم رَجُلٌ فَقَالَ ‏"‏ ائْذَنُوا لَهُ فَبِئْسَ ابْنُ الْعَشِيرَةِ ‏"‏‏.‏ أَوْ ‏"‏ بِئْسَ أَخُو الْعَشِيرَةِ ‏"‏‏.‏ فَلَمَّا دَخَلَ أَلاَنَ لَهُ الْكَلاَمَ‏.‏ فَقُلْتُ لَهُ يَا رَسُولَ اللَّهِ قُلْتَ مَا قُلْتَ، ثُمَّ أَلَنْتَ لَهُ فِي الْقَوْلِ‏.‏ فَقَالَ ‏"‏ أَىْ عَائِشَةُ، إِنَّ شَرَّ النَّاسِ مَنْزِلَةً عِنْدَ اللَّهِ مَنْ تَرَكَهُ ـ أَوْ وَدَعَهُ ـ النَّاسُ اتِّقَاءَ فُحْشِهِ ‏"‏‏.‏