In the absence of an official text, various traditions about what Muhammad might have said about different topics emerged: vacuums attract filling.
Collections, both written and spoken, appeared, presenting themselves as the words of Muhammad. These collections were not always mutually compatible. When the contradictions became evident, crisis and conflict arose.
If Islam were to continue as a viable social and political order, some harmony would be needed.
In legal matters, e.g., some foundational core of unchanging doctrines was necessary for establishing sharia. There would be some flexibility for interpretation and competing regional precedents, but there would also be fixed set of axiomatic laws.
A non-negotiable axiom within sharia is called a hadd (the plural form is hudud). The collected hudud constitute the basis of sharia and of the broader Islamic social worldview.
To formulate hudud and other invariable Islamic doctrines, early Muslim scholars began to sift through the competing collections of sayings. These collections were called hadith. In the meantime, the Qur’an was beginning to emerge in written form. The need to harmonize the hadith with each other, and with the Qur’an, was growing.
These scholars worked to form a consensus about which hadith would be regarded as authoritative, as Timothy Furnish writes:
Two aspects of individual hadiths became the focus of scholarly criticism within the early Islamic world: the matn (plural mutun or mitan), or “text,” and the isnad (plural sanad), or “chain of transmission.” A matn might well be rejected on the grounds that it seemed to contradict the Qur’an. But the focus of hadith criticism was channeled into investigating the isnads rather than the matns. The number, credibility, and seamlessness of the transmitters became more important than what the tradition actually said. And so as long as a hadith text did not actually contradict the Qur’an, it had a shot at being accepted by at least some segment of the early Islamic community, especially if what it said proved useful in some manner, usually political. Hadiths were ranked into three categories based on the trustworthiness of their chains of transmission going back to the Prophet: sahih, “sound”; hasan, “good”; and da'if, or “weak.”
So it was that Qur’an began to accumulate out of various fragments which were circulating at the time. Simultaneously, some hadith were gaining recognition as authoritative while others were being relegated to a questionable status.
Two processes were happening, and they overlapped somewhat in time: the process of composing the final edition of the Qur’an, and the process of sorting out various hadith. These two processes most probably influenced each other.
Together, the two processes formed the finished social and political order which is Islam.
This categorization was largely worked out by Muhammad b. Idris al-Shafï i (d. 820 CE), who had been disturbed by the proliferation of questionable, even downright false, traditions in his time and developed the gauge of isnad legitimacy as a means of differentiating spurious hadith from acceptable ones. If a consensus of scholars agreed a particular hadith was acceptable, then it was deemed so for the entire Islamic world.
This scholarly consensus shaped the history of Islam permanently. Not only were the Hudud fixed, but more significantly, the nature of Islam as political and social movement was determined.
The fact that modern Islam is less about the agency and personhood of the deity, and more about public and communal paradigms which humans should institute and maintain, can be traced to the formative stage of development in which the texts of Islam were accreted and given their relative degrees of authority.
