ibn Abbas · The Book on Government

One who found in his Amir something which he disliked should hold his patience, for one who separated from the main body of the Muslims even to the extent of a handspan and then he died would die the death of one belonging to the days of Jahiliyya.

There is no Hijra now, but (only) Jihad (fighting for the cause of Islam) and sincerity of purpose (have great reward) ; when you are asked to set out (on an expedition undertaken for the cause of Islam) you should (readily) do so.