What is the evidence from the Qur’an and Sunnah for the authoritativeness of a recurrent (mutawatir) report in both, and for the acceptance of a non-recurrent (ghayr mutawatir) Sunnah, and the validity of adopting the isnad (chain of transmission)?

The authoritative nature of a consecutively transmitted report (khabar mutawatir) is inherent in its definition: it is definitively established and provides necessary knowledge by itself, requiring no additional indicators or proofs. Anything that provides knowledge is considered an authoritative proof (hujjah). Scholars have unanimously agreed that a mutawatir report provides certain, necessary knowledge that admits no doubt. As for the claim that the two Sahih (definition) collections, Bukhari and Muslim, are mutawatir, this is incorrect. They contain both mutawatir and Ahad (single-chain) reports. However, the mere fact that a Hadith (definition) is narrated in them is considered among the indicators that lead to certainty of authenticity, because the Muslim community has received them with acceptance and generally agreed upon their authenticity.