that death overtook him before he could carry out his plan beyond the first tier (1). I therefore say: When you look at Muslim’s own division of the material in his book into three strata of transmitters, without any repetition, you find him stating that the first section consists of the reports of the ḥuffāẓ (the master memorisers).
He then says: “When this section is finished, I shall follow it with the reports of those who are not described as exceptionally skilful and precise.” He further notes that these narrators are to be attached to the first tier; hence, anyone who studies the chapters carefully will see that they are indeed represented in his book.

The second stratum comprises people about whom some critics spoke unfavourably while others declared them sound. Muslim therefore included their narrations only from those who had not been deemed weak or accused of innovation, and al-Bukhārī did the same.

Qāḍī ʿIyāḍ then said: “In my view, he incorporated all three of his intended strata in the book and left out the fourth (2).”

I reply: Rather, he recorded the hadiths of the first tier in full, and he also recorded the hadiths of the second tier—save for the very small number he himself rejected from among them. After that, he cited for the third-tier narrators only a limited set of reports, using them mainly as corroborating evidence, supportive parallels, and follow-ups; it is rare to find that he gave them a place in the principal chains. Had he incorporated everything transmitted by this stratum in the Sahih, the book would have doubled in size, and by virtue of such inclusion it would have fallen short of the rank of complete authenticity. Among these narrators are ʿAtāʾ ibn as-Sāʾib, Layth, Yazīd ibn Abī Ziyād, Abān ibn Ṣamʿah, Muḥammad ibn Isḥāq, Muḥammad ibn ʿAmr ibn ʿAlqamah, and others of their kind. For them he brings only an isolated report here and there when it has an established basis, whereas it is Aḥmad, in his Musnad, who frequently cites and amasses their material.