There are numerous Prophetic traditions about the Mahdi, reported by both the Sunni and the Shi'i sources. Close examination of the contents of these traditions proves that the subject of the future coming of the Mahdi and the Qa'im was a well established tenet during the Prophet's life time. People anticipated someone who would take upon himself to establish truth and spread the worship of God. Moreover, they expected that person to take charge of purifying the earth and instituting justice. The belief was so wide spread among the people that having verified it in principle they were engaged in discussing its details. Sometimes they would ask: "From which family would the awaited Mahdi arise?" At other times they wanted to know his name and patronymic. Still at other times they wanted to know the reason why he was called the Mahdi. They wanted to know about his revolution and asked about the signs of his appearance. They also wanted to find out if the Mahdi and the Qa'im were one and the same person. They were told about the Mahdi's occultation and wanted to understand the reasons and the obligations of his followers while he was in occultation. The Prophet also, from time to time, used to inform people about the existence of the Mahdi. He would inform them saying: "Mahdi will be among my descendants. He will be among the sons of Fatima, among the descendants of Husayn." At other times he would announce his name and patronymic and give information about the signs of his reappearance and other related matters.
