Hadith remembers God unceasingly. (Al-Ahzab 33: 21) The hadith literature is based on spoken reports in circulation after the death of Muhammad. Unlike the Qur'an, ahadith were not promptly written down during Muhammad's life or immediately after his death. Hadith were evaluated and gathered into large collections during the 8th and 9th centuries, generations after the death of Muhammad, after the end of the era of the "rightful" Rashidun Caliphate, over from where Muhammad lived. "Many thousands of times" more numerous than Quranic verse, ahadith have been described as resembling layers surrounding the “core” of the Islamic belief (the Quran). Well-known,
Hadith terminology "musnad" ( meaning "supported") "hadith" as: A "musnad hadith" should not be confused with the type of "hadith" collection similarly termed "musannaf", which is arranged according to the name of the companion narrating each "hadith". For example, a "musnad" might begin by listing a number of the "hadith", complete with their respective "sanads", of Abu Bakr, and then listing a number of "hadith" from Umar, and then Uthman ibn Affan and so on. Individual compilers of this type of collection may vary in their method of arranging those Companions whose "hadith" they were collecting. An example of this type of