In His Name and With The Remembrance of His Hujjat (a.t.f.s.)
Ali bin Ahmad narrated from Obaydillah bin Musa al-Alawi from Abu Muhammad Musa bin Haroon bin Eessa al-Ma’badi from Abdullah bin Maslama bin Qu’nub from Sulayman bin Bilal from Ja’far bin Muhammad as-Sadiq (s) from his father (s) from his grandfather (s) that al-Husayn bin Ali (s) had said:
“Once a man came to Amirul Mo’mineen (s) and said to him: “O Amirul Mo’mineen (s), would you tell us about your Mahdi?”
Amirul Mo’mineen (s) said: “If most of you pass away, the believers become rare and the clamorers perish, then he will appear!”
The man said: “Where from is the man (al-Mahdi)?”
Imam Ali (s) said: “He is from the Hashemites; the top of the mountain of the Arabs (the best of the Arabs), the sea, to which everyone comes ladling, the safe resort and the pure spring when others become turbid. He is from the people, who do not cower when death hastens, do not weaken when the end approaches and do not recede when the heroes clash. He is always a winner like a lion. He will do away with the oppressors and the arrogants. He is a sword of Allah’s. He arises from loftiness. His glory emits from a great glorious family. Let none of those, who hasten towards seditions and who when saying, the evilest of sayers and when keeping silent, fishing in the troubled water, prevents you from paying homage to him.
“He is the most generous, the most aware and the kindest of you to his kin. O Allah, make his advent as deliverance from distresses and make the umma unite by him! O you man, if Allah chooses (that) to you, be determined and do not deviate from him (al-Mahdi) when you are guided to him.” He sighed and pointed at his chest with his hand showing his eagerness to see him.”
 Ithbat al-Hudat, vol.3 p.537, Biharul Anwar, vol.51 p.115, Muntakhab al-Athar p.309, Mo’jam Ahadeeth al-Imam al-Mahdi, vol.3 p.59.