(20) باب بَيَانِ كَوْنِ النَّهْىِ عَنِ الْمُنْكَرِ، مِنَ الإِيمَانِ وَأَنَّ الإِيمَانَ يَزِيدُ وَيَنْقُصُ وَأَنَّ الأَمْرَ بِالْمَعْرُوفِ وَالنَّهْيَ عَنِ الْمُنْكَرِ وَاجِبَانِ
The same hadith of the Prophet (may peace and blessings be upon him) has been reported by Abu Sa'id al-Khudri in connection with the story of Marwan. (RU)
Reference (RU): Sahih Muslim 49 b (RU)
In-book reference (RU): Book 1, Hadith 85 (RU)
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 80 (RU)