Sahih Muslim , Book 33, Hadith 93 (In-Book) ⓘ
It has been narrated on the authority of 'Arfaja who said: I have heard the Messenger of Allah say: Different evils will make their appearance in the near future. Anyone who tries to disrupt the affairs of this Umma while they are united you should strike him with the sword whoever he be. (If remonstrance does not prevail with him and he does not desist from his disruptive activities, he is to be killed.)
حَدَّثَنِي أَبُو بَكْرِ بْنُ نَافِعٍ ، وَمُحَمَّدُ بْنُ بَشَّارٍ ، قَالَ ابْنُ نَافِعٍ : حَدَّثَنَا غُنْدَرٌ ، وقَالَ ابْنُ بَشَّارٍ : حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ ، حَدَّثَنَا شُعْبَةُ ، عَنْ زِيَادِ بْنِ عِلَاقَةَ ، قَالَ : سَمِعْتُ عَرْفَجَةَ ، قَالَ : سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، يَقُولُ : " إِنَّهُ سَتَكُونُ هَنَاتٌ وَهَنَاتٌ ، فَمَنْ أَرَادَ أَنْ يُفَرِّقَ أَمْرَ هَذِهِ الْأُمَّةِ وَهِيَ جَمِيعٌ ، فَاضْرِبُوهُ بِالسَّيْفِ كَائِنًا مَنْ كَانَ "
also referenced under: Hadith 1852 (Reference) & Book 20, Hadith 4565 (USC-MSA)