The Book of Occultation — al-Ṭūsī · Hadith 668 (#Ḥadīth #10)

403- الفضل بن شاذان، عن موسى بن سعدان، عن عبد الله بن قاسم الحضرمي، عن أبي سعيد الخراساني قال: قلت لابي عبد الله عليه السلام: لأي شيء سمي القائم؟ قال: لأنه يقوم بعدما يموت، إنه يقوم بأمر عظيم يقوم بأمر الله سبحانه.

H 403 - It is narrated from Fadhl bin Shazan from Musa bin Sadan from Abdullah bin Qasim Hadhrami from Abi Saeed Khurasani that he said: I asked Imam Ja’far Sadiq , “Why is he named as Qaim?” He said: “Because he will rise after his name dies. He will establish a mighty enterprise. He will rise up by the command of Allah, the Glorified.”

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