Answering the Zaydiyyah sect

This is the second part of answering the objection from the Zaydiyyah (Zaydi) sect. Part 1 is here. Note: I summarized key points from my reading and added some context.

The Zaydi sect (Zaydiyyah) has rejected Imam Musa al-Kadhim (The Seventh Shia Imam) by claiming that he (Musa al-Kadhim) in not the legitimate successor. The Zaydis believe Imam Jaffar as-Sadiq (may peace be upon him) issued a Nass (verbal acknowledgment of the candidacy) in favor of Ismail when he (Ismail) was still alive.

Ismail is believed to have passed away in the lifetime of his father (Imam Jaffar as-Sadiq). The following blog entry contains some specific of his death.

Shaykh Saduq clarified that the accusation from Zaydis are false and have no merit whatsoever. Even the tradition (below) that was presented by them to support the claim had been taken out of context

"The Almighty Allah did not effect change (Bada) in anything like He did regarding my son, Ismail".
The misinformation has been spread far and wide by irresponsible party. Please click here to see the explanation of the tradition (Bada in connection to the death of Ismail son of Imam as-Sadiq)

Shaykh Saduq asked his audience to evaluate Zaydi’s accusation critically.

What is the basis of making the above statement?
Did the Imam (as-Sadiq) really issued a nass to support the Imamah of his son Ismail?
Who witnessed the proclamation?
Who reported the incident? When did the event take place?
Can the report be trusted?

The book stated that Zaydis were not able to answer these questions convincingly.

We believe that those who believe in the Imamate of Ismail concocted the story. Ismail was not ma’sum (infallible). And only someone who is ma’sum (infallible) can become the true and absolute leader for mankind.