It was narrated from Shu'bah, from Abu Ishaq who said: "I heard Abu Al-Ahwas (narrate) that 'Abdullah said: 'Defaming a Muslim is evildoing and fighting him is Kufr.'" So Aban said to him: "O Abu Ishaq! You heard it only from Abu Al-Ahwas?" He said: "Rather, I heard it from Al-Aswad and Hubairah."
It was narrated from 'Abdur-Rahman bin 'Abdullah, from his father, that: The Messenger of Allah [SAW] said: "Defaming a Muslim is evildoing and fighting him is Kufr."
It was narrated from Shu'bah who said: "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.'"
It was narrated from Sufyan bin Zubaid, from Abu Wa'il, from 'Abdullah: "The Messenger of Allah [SAW] said: 'Defaming a Muslim is evildoing and fighting him is Kufr.'" I said to Abu Wa'il: "Did you hear it from 'Abdullah?" He said: "Yes."
Hadiths 4111https://sunnah.com/nasai:4111
أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلاَنَ، قَالَ حَدَّثَنَا مُعَاوِيَةُ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " سِبَابُ الْمُسْلِمِ فُسُوقٌ وَقِتَالُهُ كُفْرٌ " .
It was narrated that 'Abdullah said: "The Messenger of Allah [SAW] said: 'Defaming a Muslim is evildoing and fighting him is Kufr.'"
It was narrated that Abu Hurairah said: "The Messenger of Allah [SAW] said: 'Whoever parts from obedience, and splits away from the Jama'ah and dies, then he has died a death of Jahiliyyah. Whoever rebels against my Ummah, killing good and evil people alike, and does not try to avoid killing the believers, and does not pay attention to those who are under a covenant, then he is not of me. Whoever fights for a cause that is not clear, advocating tribalism, getting angry for the sake of tribalism, and he is killed, then he has died a death of Jahiliyyah.'"
It was narrated that Jundab bin 'Abdullah said: "The Messenger of Allah [SAW] said: 'Whoever fights for a cause that is not clear, advocating tribalism, getting angry for the sake of tribalism, then he has died a death of Jahiliyyah.'"
It was narrated that Abu Bakrah said: "The Messenger of Allah [SAW] said: 'If a Muslim points a weapon at his fellow Muslim, then they are on the brink of Hell, and if he kills him, then they will both fall into it.'"
It was narrated that Abu Bakrah said: "If two Muslim men bear weapons against each other, then they are both on the brink of Hell. And if one of them kills the other, they will both be in Hell."
It was narrated from Abu Musa that: The Prophet [SAW] said: "If two Muslims confront each other with swords, and one kills the other, they will both be in Hell." It was said: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He wanted to kill his companion."
It was narrated from Abu Musa Al-Ash'ari that: The Prophet [SAW] said: "If two Muslims confront each other with swords and one of them kills the other, they will both be in Hell."
It was narrated from Abu Bakrah that : The Prophet [SAW] said: "If two Muslims confront each other with swords, each of them wanting to kill the other, they will both be in Hell." It was said to him: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He was determined to kill his companion."
It was narrated that Abu Bakrah said: "The Messenger [SAW] said: 'If two Muslims meet (and fight) with their swords and one of them kills the other, the killer and the slain will both be in Hell.'"
It was narrated that Abu Bakrah said: "I heard the Messenger of Allah [SAW] say: 'If two Muslims confront each other with their swords and one of them kills the other, both the killer and the slain will be in Hell.'" They said: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He wanted to kill his companion."
It was narrated that Abu Bakrah said: "The Messenger of Allah [SAW] said: 'If two Muslims fight with swords, and one of them kills the other, then the killer and the slain will both be in Hell.'"
It was narrated from Abu Musa Al-Ash'ari that : The Messenger of Allah [SAW] said: "If two Muslims confront each other with swords and one of them kills the other, then the killer and the slain will both be in Hell." A man said: "O Messenger of Allah, (we understand about) the killer, but what about the one who is killed?" He said: "He wanted to kill his companion."
It was narrated from Ibn 'Umar that : The Prophet [SAW] said: "Do not revert to disbelievers after I am gone, striking the necks of one another (killing one another)."