Hadith 31-254

وَبِإِسْنادِهِ عَنِ النَّبِي‏ صَلَّى اللهُ عَلَيْهِ وَآلِهِ قالَ: مَن جاءَكُم يُرِيدُ أَن يُفَرِقَ الجَماعَةِ وَيَغصِبَ الاُمَّةَ أَمْرَها وَيَتَولّى مِن غَيْرِ مَشوِرَةٍ فَاقتُلُوهُ، فَإِنَّ اللَّهَ عَزَّ وَجَلَّ قَدْ أَذِنَ ذلِكَ.

According to the same documentation, it is narrated that the Prophet (S) said, “Whenever someone comes and tries to make disunion in the society and oppressively takes over the affairs of the society, you should kill him. Indeed the Honorable the Exalted God has granted this permission.”