Narrated to us my father رضي الله عنه that: Narrated to us Saad bin Abdullah: Narrated to us Muhammad bin Husain bin Abil Khattab from Abi Dawood Sulaiman bin Sufyan Mustariq from Ahmad bin Umar Hallal that he said: “I asked Abul Hasan al-Ridha عليه السلام: “It is narrated to us from Abi Abdullah عليه السلام that he either said: ‘The earth will not remain without an Imam’ or ‘it will remain without an Imam in it’; (what is the correct version?) He replied: ‘God forbid! It will not survive for a moment but that it will indeed cave into itself.’”