Where does the identification “al-dīn al-naṣīḥah” for ʿAṭāʾ ibn Yazīd’s route come from?

Historical Examples of Muʿanʿan Transmission and the Conclusion of Muslim’s Introduction

• Muslim reproduces that full matn in this sentence
• From al-Nawawī’s pertinent commentary
• From a Qur’anic verse explicitly quoted here
• From the morphological form of the narrator’s kunyah