Mansur Ilyas, governor of Jabal Nufusah on behalf of the fourth Rustumid Imam Muhammad b. Aflah. Abu Mansur fought al-Abbas b. Tulun who attacked Tripoli in the year 267H and conquered him, but left on the battlefield sixty loads of gold, not taking a single piece73. The Ibadhi scholar Abu Ya'qub al-Warijlani, reporting on this event, commented: "What a great loss!"74.

The other question was, who were true Muslims among the contending parties, and what were the others? Were they also Muslims or were they infidels? There was no denial that all those groups believed in the same God and the same Prophet. The question was about the practice of the religion. The Ibadhis' solution of this problem was based on their definition of sin. Grave sins (kabair) were divided into two groups75.

a) Grave sins falling within the category of Polytheism (kabair al-shirk). This type of sin includes:

i) Rejecting any aspect of the faith of which Muslims may not be ignorant (ما لا يسع جهله), such as Unity of God, Cognition of Allah, Prophets and Angels.

ii) To regard as permissible what is prohibited by the Qur'an such as carrion, blood, pork, slaying the soul without right, deriving profit from usury, etc. Those who commit such sins are polytheists (mushrikun).

b) Grave sins falling within the category of hypocrisy (kabair al-nifaq). This type of sins consists of:

i) Mistakenly regarding as permissible what God has forbidden (al-istihlal bi ta'wil al-khata).

ii) Committing that for which God has threatened punishment in this world and chastisement in the world to come, or for which he has punished one of the previous nations. The sinner of this nature is neither a believer (mu'min) nor a polytheist (mushrik) but a Hypocrite (munafiq) and an 'infidel-ingrate (kafir kufr ni'mah)76. This expression was used to differentiate this type of sinner from the Polytheists for whom the Arabic word kafir is also used. Ibadhi sources speak of two types of kufr: (i) kufr juhud, or kufr musawat which means to disbelieve in God or to make Him equal with others. In this sense the term kafir is synonymous with mushrik, polytheist77 (ii) Kufr ni'mah: ingratitude for the blessings of God. This term was used for those Muslims who commit hypocritical grave sins, and for those who acknowledge the faith of Islam but do not practice it78. The terms nifaq, kufr nifaq, and kufr ni'mah are used in the same sense, for Ibadhis held that hypocrisy (nifaq) is only in deeds and not in the faith79.