faith). Infallibility (Ismah) Ismah is the concept of infallibility or "divinely bestowed freedom from error and sin" in Islam. Muslims believe that Muhammad, along with other prophets and messengers in Islam, possessed ismah. Twelver and Ismāʿīlī Shīʿa Muslims also attribute the quality to Imams as well as to Fāṭimah, daughter of Muhammad, in contrast to the Zaydī Shīʿas, who don't attribute ismah to the Imams. Though initially beginning as a political movement, infallibility and sinlessness of the Imams later evolved as a distinct belief of (non-Zaydī) Shīʿīsm. According to Shīʿa Muslim theologians, infallibility is considered a rational, necessary precondition for spiritual and religious guidance. They argue that since God has commanded absolute obedience from these figures, they must only order that which is right. The state of infallibility is based on the Shīʿa interpretation of the Verse of Purification. Thus, they are the most pure ones, the only immaculate ones preserved from, and immune to, all uncleanness. It doesn't mean that supernatural powers prevent them from committing a sin, but due to the fact that they have absolute belief in God, they refrain from doing anything that is a sin. They also have a complete knowledge of God's will. They are in possession of all knowledge brought by the angels to the prophets (nabī) and the messengers (rāsūl). Their knowledge encompasses the totality of all times. Thus, they are believed to act without fault in religious matters. Shīʿa Muslims regard ʿAlī ibn Abī Ṭālib as the successor of Muhammad not only ruling over the entire Muslim community in justice, but also interpreting the Islamic faith, practices, and its esoteric meaning. Hence he was regarded as being free from error and sin (infallible), and appointed by God by divine decree (nass) to be the first Imam. ʿAlī is regarded as a "perfect man" (al-insan al-kamil) similar to Muhammad, according to the Shīʿa viewpoint. Occultation (Ghaybah) The Occultation is an eschatological belief held in various denominations of Shīʿa Islam concerning a messianic figure, the hidden and last Imam known as "the Mahdi", that one day shall return on Earth and fill the world with justice. According to the doctrine of Twelver Shīʿīsm, the main goal of Imam Mahdi will be to establish an Islamic state and to apply Islamic laws that were revealed to Muhammad. The Quran doesn't contain verses on the Imamate, which is the basic doctrine of Shīʿa Islam. Some