The Book of Occultation — al-Ṭūsī · Hadith 350 (#Ḥadīth #4)
Chapter 32 | Refutation of those who stopped at the Imamate of Imam Ja’far Sadiq and said that he is the Promised Mahdi
وأما الواقفة الذين وقفوا على موسى بن جعفر عليهماالسلام وقالوا هو فقد أفسدنا أقوالهم بما دللنا عليه من موته واشتهار الأمر فيه وثبوت إمامة ابنه الرضا عليه السلام وفي ذلك كفاية لمن أنصف.
As for the Waqifa, who stop at the Imamate of Musa Ibn Ja’far , saying that he is the Mahdi, we have invalidated their belief by proving that Imam Musa Kadhim passed away and that his death was a well-known historical reality and that his son, Imam Ridha was the Imam after him, and this much is sufficient for people of reason.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).