The earliest juristic writings on Islamic law we possess date from the beginning of the second/eighth century. There exists little or no contemporary writing concerning the laws or customs of Arabia in the pre-Islamic era, except for some minor references in the historical works of classical authors. What we know of the pre-Islamic period is therefore gleaned from information appearing in the works of Islamic writers and later oral traditions.

The number of early Islamic legal works lost or suppressed must be considerable. Early Arabic bibliographies, such as Ibn al-Nadīm's Fihrist, list many hundreds of early works by jurists whose names are now only encountered in the works of their pupils. From time to time a new book or document, a fragment or minor text is discovered in the archives of the great libraries of Damascus, Baghdad, Istanbul or north Africa, and it is likely that much more remains to be discovered.

The writings on law in the first two centuries of Islam fall into the following categories:

1. 1 The Qurʾān and the immense number of commentaries (tafsīr) that it generated.

2. 2 Collections of Traditions (Ḥadīth and books of āthār) concerning the behaviour of Muḣammad and his Companions.

3. 3 Books by the principal founders of the early schools of law, which deal in the main with sources of law (uṣūl al-fiqh), but particularly with the recognition given to subsidiary sources of law and the relation of the sources in cases of inherent conflict.