the same too can be seen in «uqdud-durar».
in the afore-mentioned book on page 258, the author narrates from the tenth chapter of «mawaddat-ul-qurba» as such:
it has come from salim-ibn-qais hallali that salman farsi said: when i went to meet the holy prophet (s.a.w.a.) i saw hussein sitting on his lap and kissing over his eyes and licking his clothes. thereafter the holy prophet (s.a.w.a.) said: you are a chief and the son of a chief. you are an imam and the son of an imam. you are a divine proof and the son of a divine proof and the father of nine divine proofs, the ninth of them shall be the qaem.
besides these one, there are still other numerous traditions and Allah-willing, we shall soon narrate them.
the author says- it does not seem likely that anyone amongst the muslims is ignorant of these nine personalities and has not known them by name. with this description there is no holding back to mentioning their names out of benediction and remembrance. the first of them is abul-hassan zain-ul-abedeen, followed by his son abu jafar muhammad baqir, followed by his son abu abdulla jafer sadeq, followed by his abul-hassan musa kazim, followed by his son abul-hassan ali ar-reza, followed by his son abu jafar muhammad jawad, followed by his son abul-hassan ali haadi, followed by his son muhammad hassan askari, followed by his son abul qasim muhammad Mahdi who is the ninth of them and the «qaem».
he said: abul qasim thaher-ibn-haroon-ibn-musa kazim narrated for me a tradition from his grand-father who said: my master jafer-ibn muhammad said: 'the pious successor shall be from my progeny and he is the Mahdi. his name is muhammad and his agnomen is abul-qasim. he shall emerge at the end of time. his mother is named as nargis and above his head is a cloud which shall provide a shadow for him from the sun. it shall accompany him wherever he goes and will call out in an eloquent voice: this is Mahdi, so obey him.'
besides this, there are some other traditions which Allah-willing we shall acquaint you with very soon.
ibn-hajar in «sawa'eq» on page 120 says: muhammad-ibn-ali baqer left behind six sons which the most learned and perfect amongst all is jafar sadeq. it was for this reason that he was made as his father's successor and legatee and people have narrated so much knowledge from him that his fame (of excellence) had engulfed all the places.