الكافي 1/4/80/25

25. A number of our people has narrated from Sa‘d ibn ‘Abdillah from Ayyub ibn Nuh who has said the following: “I said to abu al-Hassan al-Rida عليه السلام , ’I hope that you will be incharge of this task (Leadership with Divine Authority). Allah will drive it to your control with the sword now that the pledge of allegiance is offered to you and currency coins are printed in your name.” The Imam عليه السلام said, “There has been no one from us with whom letters had been exchanged, being pointed out with the gesture of fingers, questions asked and properties delivered to him but that he was murdered or died in his bed. (It will be as such) until Allah will raise for this task (Leadership with Divine Authority) a young boy from us whose birth place and upbringing would be unknown (to people) but not his ancestors.”