Sahih Muslim 1850
Sahih Muslim · Book 33: The Book on Government · The obligation of staying with the Jama'ah (main body) of the muslims when Fitn (tribulations) appear, and in all circumstances. The prohibition of refusing to obey and on splitting away from the Jama'ah
It has been narrated on the authority of Ibn 'Abdullah al-Bajali that the Messenger of Allah (ﷺ) said:
حَدَّثَنَا هُرَيْمُ بْنُ عَبْدِ الأَعْلَى ، حَدَّثَنَا الْمُعْتَمِرُ ، قَالَ سَمِعْتُ أَبِي يُحَدِّثُ، عَنْ أَبِي، مِجْلَزٍ عَنْ جُنْدَبِ بْنِ عَبْدِ اللَّهِ الْبَجَلِيِّ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ قُتِلَ تَحْتَ رَايَةٍ عُمِّيَّةٍ يَدْعُو عَصَبِيَّةً أَوْ يَنْصُرُ عَصَبِيَّةً فَقِتْلَةٌ جَاهِلِيَّةٌ " .
One who is killed under the banner of a man who is blind (to his just cause), who raises the slogan of family or supports his own tribe, dies the death of one belonging to the days of Jahiliyya.