Muḥammad b. al-Ḥasan al-'Askarī (Arabic: محمد بن الحسن العسکری) (born in 255/869), also known as Imam al-Mahdi (a) (Arabic: إمام المهدی), is the twelfth Imam in Twelver Shi'ism. He is the promised savior, who will rise one day and fill the earth with peace and justice. Imam al-Mahdi (a) has been in occultation from the early years of his life. Shi'as regard him as the Imam of the present age. Among his well-known titles are Imam al-Mahdi (the Imam of the time) and Wali l-'Asr (the guardian of the age). Imam al-Mahdi (a) became the Imam after the martyrdom of his father Imam al-Hasan al-'Askari (a) in the year 260/874, when he was five. From that time until the year 329/941, he was in contact with his followers through his Four Deputies. After that, his Major Occultation started, in which period the direct guidance and leadership of the Shi'a community rests with religious scholars. There are many hadiths transmitted from the Imams (a) about Imam al-Mahdi (a), his life, his Occultation, and his government, and many collections of such hadiths have been written. In addition to hadith collections, many works have been published about Imam al-Mahdi (a).
After Imam al-Mahdi's (a) birth, some Shi'as who were close and reliable companions of Imam al-Hasan al-'Askari (a) saw Imam al-Mahdi (a). Al-Shaykh al-Mufid mentions some Shi'as who saw Imam al-Mahdi (a) during the life of Imam al-'Askari (a): Muhammad b. Isma'il b. Musa b. Ja'far (a), Hakima bt. al-Imam al-Jawad (a), Abu 'Ali b. Mutahhar, 'Amr al-Ahwazi, and Abu Nasr al-Turayf, the servant of Imam al-'Askari (a).[34]
For example, according to a hadith, Muhammad b. 'Uthman al-'Amri and forty other people were in Imam al-Hasan al-'Askari's (a) house. The Imam (a) showed his son to them and said, "this is your Imam after me and my successor among you. Obey him and do not dispute about your religion. Otherwise, you will be disorganized and you will never see him again".[35]
A similar hadith is cited by al-Shaykh al-Tusi. He also mentioned other people who saw Imam al-Mahdi (a) in the meeting: 'Ali b. Bilal, Ahmad b. Bilal, Muhammad b. Mu'awiya b. Hakim, and Hasan b. Ayyub b. Nuh.[36]
Al-Shaykh al-Mufid also refers to other people, such as Abu 'Umar 'Uthman b. Sa'id al-Samman and his son, Abu Ja'far Muhammad b. 'Uthman, who saw Imam al-Mahdi (a) during the life of his father. Imam al-Mahdi (a) was also seen during the life of Imam al-Hasan al-'Askari (a) by people from Banu al-Rahba family from Nusaybin, Banu Sa'id, Banu Mahziyar from Ahvaz, Banu l-Rukuli from Kufa, Banu Nawbakht from Baghdad, and a group of people from Qazvin, Qom, and Jibal.[37]
According to different hadiths, the Prophet (s) has characterized Imam al-Mahdi (a) as being the most similar person to him.[70] Imam al-Hasan al-'Askari (a) also said that al-Mahdi's (a) look and moral character are the most similar to the Prophet's (s).[71] According to a hadith from Imam 'Ali (a): "when al-Mahdi (a) begins his uprising, his age will (seem to) be between thirty to forty".[72]
Imam al-Hasan al-Mujtaba (a) characterized him as a young person of at most forty years old with an endless power.[73] Imam al-Sadiq (a) describes him as a perfect middle-aged (mu'tadil) young man.[74] In a comment on this hadith, al-'Allama al-Majlisi said: "mu'tadil" in this hadith means a person in his middle ages or late young ages. In response to Abu Salt al-Hirawi's question about the signs of the Reappearance of Imam al-Mahdi (a), Imam al-Rida (a) said: "the sign is that he is very old but he looks young. An observer thinks that he is forty years old or even younger"
Imam al-Baqir (a) has quoted his father and ancestor as saying that Imam 'Ali (a) once said on his minbar: "from my progeny in end of the time, a man will appear whose face is reddish white, whose chest is broad, with strong shoulders and two moles on his back, one with the color of his skin, and the other like that of the Prophet (s)".[78]
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