For most of the first century, there was apparently an ambivalent attitude on the part of the Companions and their early Followers concerning the writing of Ḥadīth. There was both the desire to write it down for obvious benefits, and the fear that written Ḥadīth might later be confused with the Qur'ān. Later scholars started grouping Ḥadīth under titles indicating their subject matter. This type was called muşannaf. The Muwaţţa was revised several times over forty years by its author, who flourished in Medina, having studied earlier with renowned scholars there. Third/ninth-century Ḥadīth authors undertook a systematic critical study of the muḤaddiths and their material, beginning with the Prophet's Companions, although they did not subject that generation to criticism. The third/ninth century produced the greatest and largest number of musnads, the most authoritative saḤīḤs and sunans, and solidly laid the foundations of the Ḥadīth sciences.