Ayattullah Jafari wrote some commentries on Al Hujjah book, some of these commentries - in the chaptor of "the narrators of traditions or the people which are mentioned in the traditions" - are based on "Ansab" science and some of these belief commentries are about Bada, God’s will, Absence of Imam Musa al-Kazim.The most part of this article is about Imam Mahdi. The following are several topics which have been discussed and reviewed in this article: including the short and long Occultations, ideas of sunni scholars about Imam Mahdi, ideas of Ibn Khaldon, Sheikh Ahmad Muhammad Shakir. Religious orders of "Rabet al-Alam al-Islami", special and public deputies of Imam Mahdi, Shia beliefs about the location of Imam Mahdi - Sardab - and the reason of respecting it, avoidance of calling his holliness by his special name.