Waḥyu (Arabic: وَحْي, IPA: [waħj]; pl.: وُحِيّ wuḥiyy, IPA: [wuħijː]; also spelled wahi) is the Arabic word for revelation. In Islamic belief, revelations are God's word delivered by his chosen individuals – known as messenger prophets – to mankind.
Waḥyu (Arabic: وَحْي, IPA: [waħj]; pl.: وُحِيّ wuḥiyy, IPA: [wuħijː]; also spelled wahi) is the Arabic word for revelation. In Islamic belief, revelations are God's word delivered by his chosen individuals – known as messenger prophets – to mankind.
Sunnah is the body of traditions and practices of the Islamic prophet Muhammad that constitute a model for Muslims to follow. For Muslims, the sunnah is what all the Muslims of Muhammad's time supposedly saw, followed, and passed on to the next generations. However, what constitutes the Sunnah, and its interpretation, depends significantly on the specific Islamic sect and school of thought. Sunnis rely on six major canonical hadith collections to document the Sunnah, known as Kutub al-Sittah. For Shias, the sunnah is generally documented in Kutub al-'Arba'a, which give preference to hadiths attributed to the Prophet's family (Ahl al-Bayt) and the Twelve Imams. For Ibadis, the sunnah is documented in the two hadith collections Jami Sahih and Tartib al-Musnad. Sufis hold that Muhammad transmitted his sunnah, including his spiritual values, "through a series of Sufi teachers".
According to classical Islamic theories, the sunnah is embodied in the hadith: verbally transmitted records of the teachings, actions, deeds, and sayings, attributed to Muhammad. Alongside the Qur'an, the Hadith contains the divine revelations (wahy) delivered through Muhammad that make up the primary sources of Islamic law, beliefs, and theology. The sunnah is classified into different types based on Muhammad's specific words (Sunnah Qawliyyah), his actions such as habits and practices (Sunnah Fiiliyyah), and silent approvals (Sunnah Taqririyyah). However, some Muslims, such as Ahl al-Kalam and the Mu'tazilites, have distinguished between the Sunnah and Hadith, accepting the Sunnah as an authoritative practice while being critical of the Hadith's reliability as a source for Islamic law. The Quranist stance on the Sunnah varies from outright rejection to an approach that considers external sources as secondary and dependent on the Qur'an for verification.
Hadith sciences (Arabic: علم الحديث ʻilm al-ḥadīth "science of hadith") consists of several religious scholarly disciplines used by Muslim scholars in the study and evaluation of the hadith. ("Science" is used in the sense of a field of study, not to be confused with following the principles of observation and experiment, developing falsifiable hypotheses, etc. of modern science.) The hadith are what most Muslims believe to be a record of the words, actions, and silent approvals of the Islamic prophet Muhammad as transmitted through chains of narrators. Hadith science scholars aim to determine which of these records are authentic, and which may be fabricated.
For most Muslims, determining the authenticity of hadith is enormously important in Islam because along with the Quran, the Sunnah of the Islamic prophet—his words, actions, and silent approvals—are considered the explanation of the divine revelation (wahy), and the record of them (i.e. hadith) provides the basis of Islamic law (Sharia). In addition, while the number of verses pertaining to law in the Quran is relatively few, hadith, for many, give direction on everything from details of religious obligations (such as Ghusl or Wudu, ablutions for salat prayer), to the correct forms of salutations, to the importance of benevolence to servants. Thus, the "great bulk" of the rules of Islamic law are derived from hadith, along with the Quran as a primary source.
Imāmah (Arabic: إِمَامَة) means "leadership" and is a concept in Twelver theology. The Twelve Imams are the spiritual and political successors to Muhammad, the Prophet of Islam, in the Twelver branch of Shia Islam. According to Twelver theology, the successors to Muhammad are infallible human beings, who rule justly over the community and maintain and interpret sharia and undertake the esoteric interpretation of the Quran. The words and deeds of Muhammad and the Imams guide the community. For this, the Imams must be free from error and sin and chosen by divine decree—nass—through the Prophet.
Shi'a believe that divine wisdom—'Aql—is the source of the souls of the Prophets and Imams and gives them esoteric knowledge—hikmah—and that their suffering is a means by which their devotees may acquire divine grace. The Imam is not the recipient of divine revelation, but has a close relationship with God, who guides him, allowing the Imam in turn to guide others. The Imamat, or belief in the divine guide, is a fundamental belief in Shia Islam and is based on the concept that God would not leave humanity without access to divine guidance.