الكافي 1/4/80/13

13. Ali ibn Muhammad has narrated from Sahl ibn Ziyad and Muhammad ibn Yahya and others from Ahmad ibn Muhammad and Ali ibn Ibrahim from his father, all three of them from ibn Mahbub from Hisham ibn Salim from abu Hamza from abu Ishaq al-Sabi’Isma‘il from a reliable one of the companions of Amir al-Mu’minin عليه السلام who has said the following. “Amir al-Mu’minin عليه السلام once spoke the words herein below from the pulpit in Kufa and I memorized them. “O Lord it is certain that You must have a person with Your Authority on Yaour earth. Such persons would come one after the other whith Your authority over the creatures who would guide people in your religion and teach them your knowledge so that your friends would not scatter. They can be in the public sight but disobeyed or out of public sight whose reappearance would be expected. Even though their persons will be hidden form the people in peace time but their knowledge that has spread before will not be hidden from the people. Their discipline will firmly be established in the hearts of people and they will act up on them.” In another part of this sermon he has عليه السلام said, “Who would it be to have such discipline?” For this reason knowledge becomes obscure when it does not find any one to bear, protect and narrate it to others just as they have heard it from the scholars and speak truthfully from them in it. O Lord, I know that all the knowledge will not become obscure and all of its sources will not banish. You will not leave your earth without a person with Your authority over Your. He may either live in public sight but is not obeyed and followed or is afraid and hidden from public sight so that Your authority is not invalidated and Your friends are not mislead after You have granted them guidance. In fact, where are they and how many are they? They are very few in number but of very great honor and respect before Allah.”