Abstract
Significant studies have been conducted on the origins and develop-ment of Islamic law in the past years. However, in regard to the first century AH, a lack of solid identified references has raised doubts around the accuracy of the reported facts during this period. For this reason, we explored a new reliable document referred to as Risālat al-Farā’iḍ, from the first century. It is accepted that this work was first written by Zayd b. Thābit (d. 45/665) and then annotated by Abū al-Zinād (d. 130/748) who lived during both the first and second centuries. In this study, it will be determined that based on the similarity between al-Muwaṭṭa’ and Risālat al-Farā’iḍ in nearly thirty-five paragraphs, Risālat al-Farā’iḍ has served as a source in the writing process of al-Muwaṭṭa’, besides, it has revealed consistent information about ʻamal (practice) of ahl al-Medīna. Finally, through this document analysis, it will be revealed that the claim that the basic hadith collections are based not only on the oral narrations but also on the written documents will be more accurate.