The Holy Prophet Muhammad(SAW) has prophesied about several events that will occur just before the advent of the day of judgment. Among these, Rasulullah(SAW) has foretold the advent of one of his descendants, Al Mahdi (the guided one), which will materialize when the believers are severely oppressed in every corner of the world. He will fight the oppressors, unite the Muslims, bring peace and justice to the world, rule over the Arabs, and lead a prayer in Mekkah at which Isa(pbuh) (Jesus) will be present.
Throughtout the history of Islam, a few individuals -- driven either by the desperate state of Muslims in their community or a selfish pursuit of power and prestige -- laid claim to being Mahdi and found a following among the uninformed masses who were looking for salvation from the heavens. For some of these individuals (like Bab of Iran or Mirza Ghulam of India) the claim to being Mahdi was just a stepping stone to the development of heretic sects which broke away from the fold of Islam. Thus, it is at least prudent to visit the facts of this prophecy and avoid falling pray to false claimants that will appear from time to time.
As Muslims, we should remember that the prophecy about Mahdi is one that will come to pass. This prophecy, however, does not absolve the Muslim ummah from its duty to strive in the cause of Allah(SWT), oppose injustice, and seek peace and betterment of human condition. Centuries have passes from the time of the holy Prophet(SAW) and there is a good possibility that many more will expire before the advent of Al Mahdi. Muslims who are negligent in their duty hoping for a savior are committing a grave mistake and are not following the divine decrees ordained in Quran or taught by Rasulullah(SAW).
The following are the collection of Sahih (authentic) Hadith regarding Mahdi.
Hadhrat Abdullah bin Mas'ood(RA) reports from the Prophet(SAW), who said:
The world will not come to pass until a man from among my family, whose name will be my name, rules over the Arabs. (Tirmidhi Sahih, Vol. 9, P. 74; Abu Dawud, Sahih, Vol. 5, P. 207; also narrated by Ali b. Abi Talib, Abu Sa'id, Umm Salma, Abu Hurayra)
The Prophet(SAW) said: Allah will bring out from concealment al-Mahdi from my family and just before the day of Judgment; even if only one day were to remain in the life of the world, and he will spread on this earth justice and equity and will eradicate tyranny and oppression. (Musnad Ahmad Ibn Hanbal, Vol. 1, P. 99)
Hadhrat Ali(RA) narrates that Rasulullah(SAW) said: Even if only a day remains for Qiyamah to come, yet Allah will surely send a man from my family who will fill this world with such justice and fairness, just as it initially was filled with oppression. (Abu Dawood)
Ali b. Abi Talib(RA) has related a tradition from the Prophet(SAW) who informed him:
The promised Mahdi will be among my family. God will make the provisions for his emergence within a single night. (Ibn Majah, Sahih, Vol. 2, P. 519)
Hazrat Umme Salmah(RA), Prophet's wife, narrates that she heard the Prophet(SAW) say:
The promised Mahdi will be among my progeny, among the descendants of Fatima. (Abu Dawud, Sahih, Vol. 2, P. 207; Ibn Majah, Sahih, Vol. 2, P. 519)
Rasulullah(SAW) announced: The Mahdi will be of my family, of the descendants of Fatima (the Prophet's daughter). (Sunan Ibn Majah, Vol. 2, Tradition No. 4086)
The Prophet(SAW) taught: Al-Mahdi is one of us, the members of the household (Ahlul-Bayt). (Sunan Ibn Majah, Vol. 2, Tradition No. 4085)
Abu Sa'id al-Khudari(RA) narrated that the Prophet(SAW) said: Our Mahdi will have a broad forehead and a pointed (prominent) nose. He will fill the earth with justice as it is filled with injustice and tyranny. He will rule for seven years. (Abu Dawud, Sahih, Vol. 2, p. 208; Fusul al-muhimma, p. 275)
Hadhrat Abu Saeed Khudri(RA) relates that Rasulullah(SAW) said: Al Mahdi will be from my progeny. His forehead will be broad and his nose will be high. He will fill the world with justice and fairness at a time when the world will be filled with oppression. He will rule for seven years.
Hadhrat Umme Salmah(RA) narrates that Rasulullah(SAW) said: After the death of a Ruler there will be some dispute between the people. At that time a citizen of Madina will flee (from Madina) and go to Makkah. While in Makkah, certain people will approach him between Hajrul Aswad and Maqaame Ibraheem, and forcefully pledge their allegiance to him.
Thereafter a huge army will proceed from Syria to attack him but when they will be at Baida, which is between Makkah and Madina, they will be swallowed into the ground.
On seeing this, the Abdaals of Shaam as well as large numbers of people from Iraq will come to him and pledge their allegiance to him. Then a person from the Quraish, whose uncle will be from the Bani Kalb tribe will send an army to attack him, only to be overpowered, by the will of Allah. This (defeated) army will be that of the Bani Kalb. Unfortunate indeed is he who does not receive a share from the booty of the Kalb. This person (Imam Mahdi) will distribute the spoils of war after the battle. He will lead the people according to the Sunnat and during his reign Islam will spread throughout the world. He will remain till seven years (since his emergence). He will pass away and the Muslims will perform his Janazah salaat. (Abu Dawood)
The holy Prophet(SAW) said: A group of my Ummah will fight for the truth until near the day of judgment when Jesus, the son of Marry, will descend, and the leader of them will ask him to lead the prayer, but Jesus declines, saying: "No, Verily, among you Allah has made leaders for others and He has bestowed his bounty upon them. (Sahih Muslim)
It is reported from Abu Hurayra(RA) that the Prophet(SAW) said:
What will be your reaction when the son of Mary (Jesus) descends and your Imam is from among yourselves? (Sahih Muslim, bab nuzul 'isa, Vol. 2; Sahih Bukhari, kitab bad' al-khalq wa nuzul 'isa, Vol. 4)
The holy Prophet(SAW) said: What would be your situation if the Son of Mary (i.e. Jesus) descends upon you and your Imam is from among you? (Bukhari, kitabul-Anbiya, Chapter Nuzul Isa bin Maryam)
According to these reliable, authentic, and universally accepted narrations, Mahdi will: Be from among the family of Prophet(SAW), among the descendants of Fatima(RA);
Have a broad forehead and pointed noise; Appear in one night; Appear just before the day of judgment; Have same name as hazrat Muhammad(SAW); Escape from Madina to Makkah where people will pledge allegiance to him; Receive pledge and help of Iraqi people; Fight in battles; Rule over the Arabs for seven years according to Sunnah; Spread justice and equity on earth; Eradicate tyranny and oppression; Lead a prayer in Mekkah which Jesus(pbuh) will follow in; NOT be the same individual as the Promised Messiah (Jesus).
The following narrations have been taken from books on which there is no consensus among Muslim scholars. Their authenticity is in question:
The holy Prophet(SAW) said: The world will not come to an end until a man from my family (ahl al-bayt), who will be called al-Mahdi, emerges to rule upon my community. (Bihar al-anwar, Vol. 51, P. 75; Ithbat al-hudat, Vol. 1, P. 9)
Umme Salmah(RA), the wife of the Prophet, has related a tradition of the Prophet(SAW): Mahdi will be among my progeny, among the children of Fatima. (Bihar al-anwar, Vol. 51, P. 75)
Rasullullah(SAW) said: The world will not come to an end until a man from the descendants of Hussain takes charge of the affairs of the world and fills it with justice and equity as it is filled with injustice and tyranny. (Bihar al-anwar, Vol. 51, P. 66)
Abu Sa'id al-Khudari(RA) has related a tradition from the Prophet(SAW) who declared: The earth will be filled with injustice and corruption. At that time, a man from among my progeny will rise and will rule for seven or nine years and will fill the earth with justice and equity. (Ahmad b. Hanbal, Musnad, Vol. 3, P. 27)
Abu al-Hujaf(RA) quotes the Prophet(SAW) saying three times: Listen to the good news about the Mahdi! He will rise at the time when people will be faced with severe conflict and the earth will be hit by a violent quake. He will fill the earth with justice and equity as it is filled with injustice and tyranny. He will fill the hearts of his followers with devotion and will spread justice everywhere. (Bihar al-anwar, Vol. 51, P. 74)
Ali b. Abi Talib(RA) said, I asked the Prophet(SAW): "Is Mahdi going to be among our own family or from some other?" He replied: "He will be among us. God will conclude His religion through him, just as He began it with us. It will be through us that people will find refuge from sedition, just as it was through us that they were saved from polytheism. Moreover, it will be through us that God will bring their hearts together in brotherhood following the animosity sown by the sedition, just as they were brought together in brotherhood in their religion after the animosity sown by polytheism." (Bihar al-anwar, Vol. 51, P. 84; Ithbat al-hudat, Vol. 7, P. 191; Majma` al-zawa'id by `Ali b. Abi Bakr Haythami (Cairo edition), Vol. 7, P. 317)
I heard the Prophet(SAW) declare from the pulpit: The Mahdi from among my descendants, from my family, will rise at the End of Time, while the heavens will pour rain and the earth will bring forth green grass for him. He will fill the earth with justice and equity as it is filled with tyranny and injustice. (Bihar al-anwar, Vol. 51, P. 74; Ithbat al-hudat, Vol. 7, P. 9)
Abu Sa'id al-Khudari(RA) narrated that Prophet(SAW) said: Severe calamity from the direction of their ruler will befall my people during the Last Days. It will be a calamity which, in severity, shall be unprecedented. It will be so violent that the earth with injustice and corruption will shrivel for its inhabitants. The believers will not find refuge from oppression. At that time God will send a man from my family to fill the earth with justice and equity just as it is filled with injustice and tyranny. The dwellers of the heavens and the earth will be pleased with him. The earth will bring forth all that grows for him, and the heavens will pour down rains in abundance. He will live among the people for seven or nine years. From all the good that God will bestow on the inhabitants of the earth, the dead will wish to come to life again. (Ibn Hajar, al-Sawa'iq al-muharriqa, P. 161; Yanabi' al-mawadda, Vol. 2, P. 177)
Abu Hurayra(RA) narrated on behalf of the Prophet(SAW): People will pay allegiance to the Mahdi between rukn and maqam (in Mekkah). (Ibn Tawus, Kitab al-malahim wa al-fitan, P. 64.)
According to these hadith, Mahdi will: 1. Be from the Family of Prophet(SAW) and descend from Hussain(RA), son of Fatima(RA); 2. Appear at the end of time; 3. Appear when earth is filled with injustice and tyranny and believers are severely oppressed; 4. Appear when a severe earthquaker will occur and green grass will grow (presumably in Arabia); 5. Fill the earth with justice and equity; 6. Spread brotherhood, equity, and devotion among Muslims; 7. Rule over Muslim community, according to Hadith, for seven or nine years; Live and act with the qualities of the holy Prophet(SAW).
The following are narrations not attribute to the Holy Prophet(SAW) and only represent second hand narrations attributed to companions of the holy Prophet(SAW). Thus, they are included only for completeness and are unreliable.
Ammar Yasir has related: At the time when Nafs al-Zakiyya is killed a caller from the heaven will say: 'Your commander is so-and-so.' (announce Mahdi) Following it the Mahdi will emerge and fill the earth with justice and equity. (Ibn Tawus, Kitab al-malahim wa al-fitan, P. 179)
Abd Allah b. Umar mentioned the name of Mahdi in the presence of an Arab who said: Mahdi is Mu'awiya b. Abu Sufyan. Abd Allah said: It is not as you say. Mahdi is a person behind whom Jesus will offer his prayers. (Ibn Tawus, Kitab al-malahim wa al-fitan, P. 179)
Mujahid said about Mahdi: One of the Prophet's companions told me that the Mahdi will not appear until that time when Nafs al-Zakiyya will be killed. At that time he will take the command and will fill the earth with justice and equity. (Ibn Tawus, Kitab al-malahim wa al-fitan, P. 171)
Nufayl's daughter Umayra narrates that she heard Hasan b. Ali's daughter saying: This affair about which you are waiting will not occur until among you some seek to distance themselves from the others and curse each other. (Majlisi, Bihar al-anwar, Vol. 52, P. 211)
Salma b. Zafar reports that one day people were talking about the appearance of the Mahdi in the presence of Hudhayfa. Hudhayfa said: If Mahdi has indeed appeared while you are living close to the Prophet's period and while his companions are living among you, then you are truly fortunate. However, that is not the case. Mahdi will not appear until people are devoured by oppression and tyranny and there is no one absent more beloved and more needed than him. (Kitab al-hawi li al-fatawa, Vol. 2, P. 159)
These narrations are based on opinion of single individuals and are not reliable. However, they indicate that Mahdi might: 1. Not appear until all Muslims are divided and curse each other (i.e. no brotherhood);
2. Appear when tyranny and oppression rule and no Muslim is free; 3. Be announced by a voice from heavens; 4. Fill the earth with justice and equity; 5. Lead the prayer which Jesus(pbuh) will follow.
The following narration has not been attributed to the Holy Prophet(SAW). It has been identified as false and has been rejected by Muslim scholars for centuries.
Amr son of Shamer quoted Jabir, who quoted Mohammed bin Ali to have said: For our Mahdi, there are two signs. Since the birth of Universe, these events have never taken place.
Those two signs are that there will be Lunar Eclipse on the first night of Ramadhan and Solar Eclipse in the middle of Ramadhan. (Dar-e-Qatni, Vol. 1, P.188)