What is Narrated From Al-Ridha عليه السلام Regarding the Designation of Al-qa'im

4 - Narrated to us Ahmad bin Muhammad bin Yahya al-Attar رضي الله عنه: Narrated to us my father from Muhammad bin Ahmad from Muhammad bin Mehran from his uncle Ahmad bin Zakariya that: Ar-Reza Ali bin Musa عليه السلام asked me:
“Where is your house in Baghdad?” I said, “At al-Karkh.” He said, “That is the safest of places. There has to happen the deaf catastrophe mischief in which every secret and close relation will be dropped. That will happen after the Shia will miss my third descendant.”