Narrated to us Muhammad bin Ahmad Shaibani رضي الله عنه : Narrated to us Ahmad bin Yahya bin Zakariya al-Qattan: Narrated to us Bakr bin Abdullah bin Habib: Narrated to us Fadl bin Saqr Abdi: Narrated to us Abu Muawiyah from Sulaiman bin Mehran Amash from As-Sadiq Ja’far bin Muhammad from his father Muhammad bin Ali from his father Ali bin Husain عليه السلام that he said:
  “We are the Imams of the Muslims, and the proofs of Allah on the whole universe. We are chieftains of the believers, and the brilliant-faced guides and we are having absolute authority on the believers. We are such a security for people on the earth, like the stars are for the dwellers of the heavens. And those for whose sake the Almighty Allah has restrained the heaven from falling into the earth and secured the earth from shaking up those who dwell upon it. The rain falls due to us and the blessings of the earth are distributed and are brought out of the earth.
If none of us remains on the earth, it would swallow its dwellers, and the Almighty Allah has not left the earth without a Proof (Hujjat) since the time of the creation of Prophet Nuh عليه السلام, whether it is apparent and obvious or unseen and hidden. And the earth shall not be devoid of Proof till the Doomsday occurs. If there is no Proof of Allah, none would worship the Almighty. Someone asked: Then how would people derive benefit from an unseen and hidden proof? The Imam replied: “Just as they receive benefits from the sun that is hidden behind the clouds.”