Amir al-Mu’minin (as) said: The Messenger of Allah (s) sent people on an expedition. When they returned, he said: Greetings to a people who completed the minor struggle (jihad); the major struggle remains for them. It was said: O Messenger of Allah! What is the major struggle? He said: The struggle against the self. Then, he (s) said: The best struggle is the struggle against the self that is between his two sides.