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 of my Hadith, if it agrees with the Holy Book of Allah, it is genuine, but whatever comes to you that does not agree with the book of Allah you must know that I have not said it.' The hadith had a profound and controversial influence on "tafsir" (commentaries of the Quran). The earliest commentary of the Quran known as Tafsir Ibn Abbas is sometimes attributed to the companion Ibn Abbas. The hadith were used in forming the basis of "Sharia" (the religious law system forming part of the Islamic tradition), and "fiqh" (Islamic jurisprudence). The hadith are at the