Mishkat al-Masabih 18 The Offices of Commander and Qadi كتاب الإمارة والقضاء 18

وَعَنْهُ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «مَنْ أَتَاكُمْ وَأَمْرُكُمْ جَمِيعٌ عَلَى رَجُلٍ وَاحِدٍ يُرِيدُ أَنْ يَشُقَّ عَصَاكُمْ أوْ يُفرِّقَ جماعتكم فَاقْتُلُوهُ» . رَوَاهُ مُسلم

He told that he heard God’s Messenger say, “If anyone comes to you when you are united under one man desiring to split you or cause parties in your community, kill him.” Muslim transmitted it.