Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
nasai:4109 – Maḥmūd b. Ghaylān > Abū Dāwud > Shuʿbah > Liḥammād > Manṣūr And Sulaymān Wazubayd Yuḥaddithūn > Abū Wāʾil > ʿAbdullāh

"I said to Hammad: 'I heard Mansur, and Sulaiman, and Zubaid narrating from Abu Wa'il, from 'Abdullah, that the Messenger of Allah [SAW] said: "Defaming a Muslim is evildoing and fighting him is Kufr." - Who are you worried about? Are you worried about Mansur? Are you worried about Zubaid? Are you worried about Sulaiman?' He said: 'No, but I am worried about Abu Wa'il.'"  

النسائي:٤١٠٩ – أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلاَنَ قَالَ حَدَّثَنَا أَبُو دَاوُدَ قَالَ حَدَّثَنَا شُعْبَةُ قَالَ قُلْتُ لِحَمَّادٍ سَمِعْتُ مَنْصُورًا وَسُلَيْمَانَ وَزُبَيْدًا يُحَدِّثُونَ عَنْ أَبِي وَائِلٍ عَنْ عَبْدِ اللَّهِ

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ مَنْ تَتَّهِمُ أَتَتَّهِمُ مَنْصُورًا أَتَتَّهِمُ زُبَيْدًا أَتَتَّهِمُ سُلَيْمَانَ قَالَ لاَ وَلَكِنِّي أَتَّهِمُ أَبَا وَائِلٍ  

See similar narrations below:

Collected by Nasāʾī's Kubrá
nasai-kubra:3561 – Maḥmūd b. Ghaylān > Abū Dāwud > Shuʿbah > Liḥammād > Manṣūr And Sulaymān Wazubayd Yuḥaddithūn > Abū Wāʾil > ʿAbdullāh

"I said to Hammad: 'I heard Mansur, and Sulaiman, and Zubaid narrating from Abu Wa'il, from 'Abdullah, that the Messenger of Allah [SAW] said: "Defaming a Muslim is evildoing and fighting him is Kufr." - Who are you worried about? Are you worried about Mansur? Are you worried about Zubaid? Are you worried about Sulaiman?' He said: 'No, but I am worried about Abu Wa'il.'" (Using translation from Nasāʾī 4109)  

الكبرى للنسائي:٣٥٦١ – أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلَانَ قَالَ حَدَّثَنَا أَبُو دَاوُدَ قَالَ حَدَّثَنَا شُعْبَةُ قَالَ قُلْتُ لِحَمَّادٍ سَمِعْتُ مَنْصُورًا وَسُلَيْمَانَ وَزُبَيْدًا يُحَدِّثُونَ عَنْ أَبِي وَائِلٍ عَنْ عَبْدِ اللهِ

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ» مَنْ تَتَّهِمُ أَتَتَّهِمُ مَنْصُورًا؟ أَتَتَّهِمُ زُبَيْدًا؟ أَتَتَّهِمُ سُلَيْمَانَ؟ قَالَ لَا وَلَكِنِّي أَتَّهِمُ أَبَا وَائِلٍ