“This is concerning my question before abu ‘ Abd Allah (a.s.), It Jihad Sunnah (optional) or obligatory?’ He replied, ‘Jihad is of four kinds. Two kinds of Jihad are obligatory and there is an optional Jihad which cannot be established without obligatory Jihad. ‘Of the two obligatory Jihad is one’s Jihad (struggle) against his soul’s desires to disobey Allah, the Most Majestic, the Most Glorious, and this is the greatest form of Jihad. Jihad against the unbeliever (declared) enemies nearby is also obligatory. ‘The kind of optional Jihad, which cannot be established without an obligatory Jihad, is when it becomes obligatory upon the whole nation to fight the enemy; and if they disregard such Jihad torment descends upon them. This is the punishment for the nation. Only for the Imam this is optional. He faces the enemy with the support of the nation to fight. ‘The optional Jihad is every optional institution for the establishment of which one strives hard to accomplish and revive. Working and the pursuit of such task is of the most excellent deeds; it is reviving of a tradition. The Messenger of Allah has said, ‘Whoever establishes a noble tradition he gains the reward therefor and a reward equal to the reward of those who act upon such noble tradition up to the Day of Judgment without any reduction in the rewards of anyone of them.’”