most important task of explaining and illustrating" the Quran. And We have also sent down unto you (O Muhammad) the reminder and the advice (the Quran), that you may explain clearly to men what is sent down to them, and that they may give thought. And We have not sent down the Book (the Quran) to you (O Muhammad), except that you may explain clearly unto them those things in which they differ, and (as) a guidance and a mercy for a folk who believe. [Quran 16:64] For example, while the Quran presents the general principles of praying, fasting, paying zakat, or making pilgrimage, they are presented "without the illustration found in Hadith, for these acts of worship remain as abstract imperatives in the Qur’an". Types of sunnah Sunnah upon which fiqh is based may be divided into: Sunnah Qawliyyah - the sayings of Muhammad, generally synonymous with “hadith”, since the sayings of Muhammad are noted down by the companions and called "hadith". Sunnah Fiiliyyah - the actions of Muhammad, including both religious and worldly actions. Sunnah Taqririyyah - the approvals of Muhammad regarding the actions of the Companions which occurred in two different ways: When Muhammad kept silent for an action and did not oppose it. When Muhammad showed his pleasure and smiled for a companion's action. It may be also divided into sunnah that is binding for Muslims and that which is not. Ibn Qutaybah (213-276 AH) distinguished between: Sunnah "brought by Gabriel"; sunnah from "Muhammad's own ra'y and is binding, but subject to revision"; "non-binding sunnah", which Muslims are not subject to "penalty for failure to follow". In the terminology of fiqh (Islamic jurisprudence), sunnah denotes whatever though not obligatory, is "firmly established (thabata) as called for (matlub)" in Islam "on the basis of a legal proof (dalîl shar`î). Sciences of sunnah According to scholar Gibril Fouad Haddad, the "sciences of the Sunnah" ('ulûm as-Sunna) refer to: the biography of the Prophet (as-sîra), the chronicle of his battles (al-maghâzî), his everyday sayings and acts or "ways" (sunan), his personal and moral qualities (ash-shamâ'il), and the host of the ancillary hadîth sciences such as the circumstances of occurrence (asbâb al-wurûd), knowledge of the abrogating and abrogated hadîth, difficult words (gharîb al-hadîth), narrator criticism (al-jarh wat-ta`dîl), narrator biographies (al-rijâl), etc., as discussed in great detail in the authoritative books of al-Khatîb al-Baghdâdî. Sunnah in Shia Islam Shia Islam does