The Book of Occultation — al-Ṭūsī · Hadith 302 (#Ḥadīth #10)
Chapter 27 | Traditions of the Holy Imams on the occultation of Imam Mahdi
122- سعد بن عبد الله عن الحسن بن علي الزيتوني عن الزهري الكوفي عن بنان بن حمدويه قال: ذكر عند أبي الحسن العسكري عليه السلام مضي أبي جعفر عليه السلام فقال: ذاك إليّ ما دمت حياً باقياً. ولكن كيف بهم إذا فقدوا من بعدي؟
H 122 - It is narrated from Saad bin Abdullah from Hasan bin Ali Zaituni from Zuhri Kufi from Banan bin Hamdawayh that he said: The passing away of Imam Ali Naqi was mentioned before Imam Hasan Askari . He said: “That is so long as I am alive and remaining. However, how would it be like when they miss the one after me?”
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).