("Science" is used in the sense of a field of study, not to be confused with following the principles of observation and experiment, developing falsifiable hypotheses, etc.
The hadith are what most Muslims believe to be a record of the words, actions, and the silent approval of the Islamic prophet Muhammad as transmitted through chains of narrators.
In addition, while the number of verses pertaining to law in the Quran is relatively few, hadith, for many, give direction on everything from details of religious obligations (such as Ghusl or Wudu, ablutions[3] for salat prayer), to the correct forms of salutations,[4] and the importance of benevolence to slaves.
[17] According to Islamic tradition, Umar ibn al-Khattab, the second caliph, started the process of collecting all the hadiths together into one unified volume, but gave up the endeavor "for fear the Quran would be neglected by the Muslims" (according to Muhammad Zubayr Siddiqi).
[Note 3] Traditional accounts describe "the systematic study of hadith" as being motivated by the altruism of "pious scholars" seeking to correct this problem.
[21] Reinhart finds descriptions of famous companions of Muhammad in Ibn Sa'd's Kitāb aṭ-ṭabaqāt al-kabīr "recording hadith and transmitting it, asking each other about precedents, and reproaching those who disregarded this authentic religious knowledge" in suspicious conformity to the "mythology of the pristine early community".
[23] Transmitters must have lived during the same period, they must have had the opportunity to meet, and they must have reached sufficient age at the time of transmission to guarantee their capacity to transmit.
[44] Al-Khatib al-Baghdadi, stating likewise, cited various evidences for this, from them, the Quranic verse, “And you were the best nation brought about to mankind.”[45] The fitnah referred to is the conflicting ideologies of the Kharijites and the Ghulat that had emerged at the time of the third Caliph Uthman ibn Affan, his assassination and the social unrest of the Kharijites in opposition to the succeeding rulers, Ali and Muawiyah.
[47] According to scholar Daniel Brown, in traditional hadith sciences, "the possibility" of criticizing the matn as well as the isnad "was recognized in theory, but the option was seldom systematically exercised".
[48] Syrian hadith scholar Salah al-Din al-Idlibi is an expert in the relatively new field of matn criticism.
According to Muhammad Husayn Haykal, "despite the great care and precision of the Hadith scholars, much of what they regarded as true was later proved to be spurious.
[56][57] Modern Western scholars in particular have "seriously questioned the historicity and authenticity of the hadith", according to John Esposito, maintaining that "the bulk of traditions attributed to the Prophet Muhammad were actually written much later."
"[Note 5] Goldziher writes that "European critics hold that only a very small part of the ḥadith can be regarded as an actual record of Islam during the time of Mohammed and his immediate followers.
"[Note 6] In his Mohammedan Studies, Goldziher states: "it is not surprising that, among the hotly debated controversial issues of Islam, whether political or doctrinal, there is not one in which the champions of the various views are unable to cite a number of traditions, all equipped with imposing isnads".
[61] Patricia Crone noted that early traditionalists were still developing conventions of examining the chain of narration (isnads) that by later standards were sketchy/deficient, even though they were closer to the historical material.