The Book of Occultation — al-Ṭūsī · Hadith 651 (#Ḥadīth #1)
Chapter 48 | Appointees of the four special deputies of the Imam
وقد كان في زمان السفراء المحمودين أقوام ثقات ترد عليهم التوقيعات من قبل المنصوبين للسفارة من الأصل.
During the period of the special deputies of Imam Mahdi there were reliable individuals for whom the emissaries and deputies of the Imam have issued epistles.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).