Sahih Bukhari Volume 8, Book 78, Hadith 6056

حَدَّثَنَا صَدَقَةُ بْنُ الْفَضْلِ، أَخْبَرَنَا ابْنُ عُيَيْنَةَ، سَمِعْتُ ابْنَ الْمُنْكَدِرِ، سَمِعَ عُرْوَةَ بْنَ الزُّبَيْرِ، أَنَّ عَائِشَةَ ـ رضى الله عنها ـ أَخْبَرَتْهُ قَالَتِ، اسْتَأْذَنَ رَجُلٌ عَلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏"‏ ائْذَنُوا لَهُ بِئْسَ، أَخُو الْعَشِيرَةِ أَوِ ابْنُ الْعَشِيرَةِ ‏"‏‏.‏ فَلَمَّا دَخَلَ أَلاَنَ لَهُ الْكَلاَمَ قُلْتُ يَا رَسُولَ اللَّهِ قُلْتَ الَّذِي قُلْتَ، ثُمَّ أَلَنْتَ لَهُ الْكَلاَمَ قَالَ ‏"‏ أَىْ عَائِشَةُ، إِنَّ شَرَّ النَّاسِ مَنْ تَرَكَهُ النَّاسُ ـ أَوْ وَدَعَهُ النَّاسُ ـ اتِّقَاءَ فُحْشِهِ ‏"‏‏.‏

Narrated By 'Aisha : A man asked permission to enter upon Allah's Apostle. The Prophet said, "Admit him. What an evil brother of his people or a son of his people." But when the man entered, the Prophet spoke to him in a very polite manner. (And when that person left) I said, "O Allah's Apostle! You had said what you had said, yet you spoke to him in a very polite manner?" The Prophet said, "O 'Aisha! The worst people are those whom the people desert or leave in order to save themselves from their dirty language or from their transgression."