What critical lesson is illustrated by the discussion of ʿAbd al-Razzāq al-Ṣanʿānī?

Innovation, Defective Retention, Ikhtilāṭ and Ḥasan li-Ghayrihi

• Investigate when different students heard their teacher
• Grade all reports identically without research
• Declare every report in the book fabricated
• Assume all students heard at the same time