Nahj al-Balagha (Peak of Eloquence)

About the division of the community into factions So now, certainly, Allāh did not break the neck of any unruly tyrant in this world except after allowing him time and opportunity and did not join the broken bone of any people (ummah) until He did not inflict calamity and distress upon them. Even less than what sufferings and misfortunes have yet to fall upon you or have already befallen you are enough for giving lessons. Every man with a heart is not intelligent, every ear does not listen and every eye does not see. I wonder, and there is no reason why I should not wonder, about the faults of these groups who have introduced alterations in their religious pleas, who do not move on the footsteps of their Prophet nor follow the actions of the vicegerent. They do not believe in the unknown and do not avoid the evil. They act on the doubts and tread in (the way of) their passions. For them good is whatever they consider good and evil is whatever they consider evil. Their reliance for resolving distresses is on themselves. Their confidence in regard to dubious matters is on their own opinions as if every one of them is the Leader (Imām) of himself. Whatever he has decided himself he considers it to have been taken through reliable sources and strong factors.