Sunan Abi Dawud, Hadith 4744 ⓘ
‘Arfajah told that he heard the Messenger of Allah (May peace be upon him) as saying : various corruptions will arise in my community, so strike with sword the one who tries to cause separation in the matter of Muslims when they are united, whoever he be.
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، عَنْ زِيَادِ بْنِ عَلاَقَةَ، عَنْ عَرْفَجَةَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ : " سَتَكُونُ فِي أُمَّتِي هَنَاتٌ وَهَنَاتٌ وَهَنَاتٌ، فَمَنْ أَرَادَ أَنْ يُفَرِّقَ أَمْرَ الْمُسْلِمِينَ وَهُمْ جَمِيعٌ فَاضْرِبُوهُ بِالسَّيْفِ كَائِنًا مَنْ كَانَ " .
also referenced under: Hadith 4762 (DarusSalam)