The Book of Occultation — al-Ṭūsī · Hadith 426 (#Ḥadīth #27)
Chapter 34 | Evidence of the Birth of the Master of the Age
قال أبونعيم: فلقيت كاملا فسألته عن هذا الحديث فحدثني به.
Abu Naeem says: I met Kamil and asked him about this tradition and he narrated the same to me.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).