" Mujāhada, a collateral form of jihād (the so-called "holy war"), taken [by Sufis] to mean "earnest striving after the mystical life." The term is based on the Koranic text, "And they that strive earnestly in Our cause, them We surely guide upon Our paths." A Tradition makes the Prophet rank the "greater warfare" (al jihad al-akbar) above the "lesser warfare" (al jihad al-asghar, i.e., the war against infidelity), and explain the "greater warfare" as meaning "earnest striving with the carnal soul" (mujāhadat al-nafs). "

― A.J. Arberry , Sufism: An Account of the Mystics of Islam