According to the well-known opinion Imami scholars are divisible into two major groups: early and recent scholars. There are several differences between the two groups in various areas of science, including hadith principles and issues. Our information about the first group’s principles of hadith scholarship is low, and in some cases limited to general reports of the scholars of the recent generation. Taking into consideration the fundamental differences of hadith principles of the two groups, they have also attempted to explain the basics of the first group, for example, the great emphasis they have placed on the early hadith scholars’ reliance on the system of evidences as a focal point of hadith assessment. Analytical and critical study of the historical reports of the early Imami scholars indicates the central role of the written source analysis among their numerous evidences. These studies indicate that the early hadith works - with different titles such as "kitab", "asl", "juz" and "nusakh" - regardless of their authors are of high status in the early Imami scholars’ hadith scholarship. Existing reports show that these scholars have sometimes considered a hadith text as reliable and valid based on the different reasons and evidence and finally verified the existing hadiths within it. This article attempts to explain the early Imami scholars’ emphasis on "book-based" components such as the notability of the book, its popularity among hadith scholars, and special attention to the reliable usuls, while mentioning a variety of examples.

Key Words: Hadith Sources, Hadith Criticism, Source Credibility, Early