The vast majority of Muslims believe that, after the Quran, sunnah is the most important source of knowledge about Islam. Wrong interpretation of the concept of Islam's universality, maximum expectation of fiqh and limitation of religious guidance to following jurisprudential rules have enhanced the importance of this source. Considering the Quran and sunnah authoritative, especially in religious principles, does not imply that these two are comprehensive and sufficient to satisfy all needs and be independent of human intellect and experience. Some questions and doubts have been raised about the authority and origin of sunnah, its coverage and permanence, its relation to the Quran, and its role in fulfilling the goals of religion and guiding people, which are analyzed cogently, convincingly and intensively in this paper. In this regard, most researchers believe that the authority of the Prophet (p.b.u.h.), the ahl al-bayt (a.s.) and the Companions’s words must be derived from the Quran and sunnah cannot be used as a legislation source independently of the Quran. The Prophet’s (p.b.u.h.) speech is a manifestation of his pure Quranic character and his ijtihad and it can have religious authority, at least, if the Quran is silent about it. His practical way of life is based on the guidance of revelation and revival of Abrahamic traditions which were known to the Quraysh and a community known as Hanefa or Saebi practiced them. Contrary to the hadiths from the Prophet, there is less apprehension about disremembering his practical way of life, distorting it or mingling it with Quran; hence, the prohibition of recording it during the Divine legislation era was unnecessary. Nevertheless, aside from the documentational weakness of the narrations prohibiting hadith recording, this prohibition cannot be considered general and permanent. However, it should be noted that there is no definite authenticity about the origin of hadiths and yet, in contrast to ideological dogmas, absolute certainty and cognizance of subordinate principles and rules is not necessary.