الكافي 1/4/80/20

20. Muhammad ibn Yahya and Ahmad ibn Idris have narrated from al-Hassan ibn Ali al-Kufi from Ali ibn Hass’an from his paternal uncle, ‘Abd al-Rahman ibn Kathir from Mufaddal ibn ‘Umar who has said the following. “I heard abu ‘Abdallah عليه السلام say, “The in charge of this task (Leadership with Divine Authority) will disappear from the public sight twice. From one them he will return to his family but in the other one it will be said that he is dead or no one knows in which of the valleys has he traveled.” I then asked, “What shall we do in such conditions?” The Imam عليه السلام said, “If any one would claim to have such authority you then should ask him about several things in which he must answer like him (Leader with Divine Authority).”