The first person who due to ignorance of Imam Mahdi (hgr)’s birth, denied the birth of Imam Mahdi (hgr), was Ja’afar (the Imam’s uncle)!
Ja’afar used to strongly inhibit the news of the Imam’s birth!!
Ibn-e-Hazm in the book “Al-Fasl fil-Milal…” impeached [Imam Mahdi’s (hgr)]’s birth. He wrote that Imam Mahdi’s (hgr)’s birth didn’t occur till Imam Askari (pbuh)’s martyrdom!
[Imam Askari (pbuh) said:] Dear aunt! Tonight, when is mid of Sha’aban, break your fast in our home; because tonight God will make you happy and glad via [visiting] his proof for ummah [people] and my successor [imam Mahdi (hgr)].
Hakimah (aunt of imam Askari) said: we recited Maghreb (vespers) and Isha (evening) prayers and broke our fast. I constantly have watched out her.
Do you know there are a lot of narrations in Shia’s sources, which mentioned the number of twelve Imams?
Shaykh Ḥorr-e ʿĀmelī in the second volume of the valuable book “Ithbat Al-hudat” has gathered nine hundred and twenty seven narrations about the imamate1 of twelve Imams, which in most of them the number and name of Imams have been mentioned straightforward.
The content [of the narrative]:
[Prophet Muhammad (pbuh&h) stated:]
“O people! Indeed I’m a human [like the others] and presently will be called [by the angel of death]…
One hundred and eighteen narratives have been handed down to us, which point that the Earth would never be without God’s proof.
Allame Majlesi collected these narratives in the chapter “Al-Iztirar Ela al-Hujjah” [Necessity of God’s proof] of Biḥār al-ʾAnwār
Also the late Kulayni has mentioned such narratives in the book “Kāfī”; the chapter “Kitab Al-Hujjah”. For example:
Prophet Muhamad (pbuh & h) and Imams have informed about the birth of a baby for Imam Hasan Askari, who has hidden after he was born.
Statistics of collected narrations, in this area, in the book “Kamal Al-Din”, as follows:
From prophet Muhamad (pbuh & h); forty five narrations
From Imam Ali (pbuh)…
From majesty Zahra (pbuh); four narrations
From Imam Hasan (pbuh); tow narrations
From Imam Hussain (pbuh); five narrations
Shiites – and also Sunnis – believe that prophet Muhamad (pbuh&h) declared the survival and dignity of Islam until the Day of Judgment, due the twelve caliphs
Sunnis have been unable to introduce these people, but in Shiites’ teaching, these twelve divine caliphs have been known and specified.
Jabir 1said, “I was in.. presence of God’s messenger [prophet Muhamad (pbu h & h)] and I heard that he stated,”
“Due to existence of twelve caliphs, duty and condition of Ummah [people] are continuously obvious.”
Ahmad ibn Hanbal (of the Sunni elders) has written on page 86 of volume 5 of In his book “Musnad”:
“Jabir has narrated this narration via 34 ways.”