The Book of Occultation — al-Ṭūsī · Hadith 378 (#Ḥadīth #27)

وأما من ذهب إلى الفترة بعد الحسن بن علي عليهما السلام وخلو الزمان من إمام، فقولهم باطـل بمـا دللنـا عليـه مـن أن الزمـان لا يخلـو عن إمـام في حـال من الأحـوال بأدلـة عقليـة وشرعية وتعلقهم بالفترات بين الرسل باطل لأن الفترة عبارة عن خلو الزمان من نبي ونحن لا نوجب النبوة في كل حال وليس في ذلك دلالة على خلو الزمان من إمام على أن القائلين بذلك قد انقرضوا ولله الحمد فسقط هذا القول أيضا.

As for those who believe that time remains devoid of an Imam after Imam Hasan Askari , their belief is invalid, because we have proved through rational as well as narrational proofs that time does not remain devoid of an Imam in any condition. Their argument that there were times when there were no prophets cannot benefit them, since we don’t believe that there has to be a prophet in every age and such an assertion does not prove the possibility that an era can be without an Imam. Besides, the followers of this creed have perished as well, and praise belongs to the Lord. Therefore, this belief is also invalid.

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).