Concerning the Prophet and his Household he says...

Concerning the Prophet and his Household he says, "Allah's wish is but to remove uncleanness far from you, O Folk of the Household, and cleanse you with a thorough cleansing" (Quran, XXXIII, 33). As proved by these verses, the Holy Quran emanates from sources beyond the comprehension of common man. No one can have a full comprehension of the Quran save those servants of God whom He has chosen to purify. And the Household of the Prophet are among those pure beings.

In another place God says, "Nay, but they denied that (the Quran), the knowledge whereof they could not compass, and whereof the interpretation (in events) [ta'wil] hath not yet come into them" (Quran, X, 40) (meaning the day of Resurrection when the truth of things will become known).

And again he says, "On the day (the Day of Resurrection) when the fulfillment [ta'wil] thereof (of the whole Quran) cometh, those who were before forgetful thereof will say: The messengers of our Lord did bring the Truth!" (Quran, VII, 53) Hadith The principle that the hadith possesses validity, as attested by the Quran, is not at all disputed among Shi'ites or in fact among all Muslims.

But because of the failure of some of the early rulers of Islam in preserving and guarding the hadith, and the excesses of a group among the companions and followers of the Prophet in propagating hadith literature, the corpus of hadith came to face a certain number of difficulties. On the one hand the caliphs of the time prevented the writing down and recording of the hadith and ordered any pages containing texts of hadith to be burned.

Sometimes also any increase in activity in the transmission and study of hadith was forbidden. In this way a certain number of hadiths were forgotten or lost and a few were even transmitted with a different or distorted meaning. On the other hand another tendency also prevailed among another group of the companions of the Holy Prophet who had had the honor of seeing his presence and actually hearing his words.

This group, which was respected by the caliphs and the Muslim community, began an intense effort to propagate the hadith. This was carried to such an extent that sometimes hadith overruled the Quran and the injunction of a Quranic verse was even considered abrogated by some people through a hadith. Often the transmitters of hadith would travel many miles and bear all the difficulties of traveling in order to hear a single saying.