Holy Prophet (s.a.w.a.) informed Ammar bin Yasir – Soon there will be confusion after me in my nation till swords are drawn out and some are killed by others and a group does tabarra from another group. When you witness this, then it is mandatory for you to hold on to this bald one on my right i.e. Ali bin Abi Talib (a.s.). If all the people venture into a valley and Ali (a.s.) ventures into another valley, then you must head for the valley of Ali (a.s.) and abandon the people. O Ammar, Ali (a.s.) will never turn you away from guidance and will never guide you towards destruction. O Ammar, obedience to Ali (a.s.) is obedience to me and obedience to me is obedience to Allah, the Almighty.
Kashf al-Yaqeen Fi Fazaael Ameeril Momineen (a.s.) p 161 Bashaarah al-Mustafa Le Shiah al-Murtaza v 2 p 146 Al-Umdah p 451 Tarf min al-Amba wa al-Manaqib p 460