The Book of Occultation — al-Ṭūsī · Hadith 565 (#Ḥadīth #13)
Chapter 43 | Special Emissaries of the Imam during the Occultation
فلما مضى أبوعمرو عثمان بن سعيد قام ابنه أبوجعفر محمد بن عثمان مقامه بنص أبي محمد عليه السلام عليه ونص أبيه عثمان عليه بأمر القائم عليه السلام.
When Abu Amr Uthman Ibn Saeed died, his son Abu Ja’far Muhammad Ibn Uthman stood in his place, as the representative of the Qaim on the virtue of clear instructions of Imam Hasan Askari and the instructions of his father.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).