(38) باب لَمْ يَكُنِ النَّبِيُّ صلى الله عليه وسلم فَاحِشًا وَلاَ مُتَفَحِّشًا
Narrated 'Aisha:
A man asked permission to enter upon the Prophet. When the Prophet (ﷺ) sawhim, he said, "What an evil brother of his tribe! And what an evil sonof his tribe!" When that man sat down, the Prophet (ﷺ) behaved with him ina nice and polite manner and was completely at ease with him. When that person had left, 'Aisha said (to the Prophet). "O Allah's Apostle! When you saw that man, you said so-and-so about him, then youshowed him a kind and polite behavior, and you enjoyed his company?" Allah's Messenger (ﷺ) said, "O 'Aisha! Have you ever seen me speaking a bad and dirty language? (Remember that) the worst people in Allah's sight on the Day of Resurrection will be those whom the people leave (undisturbed) to be away from their evil (deeds)."
Reference: Sahih al-Bukhari 6032
In-book reference: Book 78, Hadith 62
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 73, Hadith 59