Hazrat Anas (radiAllahu anhu) recounted the words of Hazrat Malik (radi Allahu anhu) . He said that the Messenger of Allah (sallallhu alayhi wasslam)) stated:The life span of the world is seven days in the afterlife days. Almighty Allah said that a day in the sight of the Lord is like a thousand of your years.(Suyuti, Al-Kashf 'an (fi) Mujawazat Hadihi l-umma al-Alf, al-Hawi lil Fatawi, p. 10)Anas ibn Malik (radi Allahu anhu) narrates that the Messenger of Allah (sallallahu alayhi wassallam) said: Allah will ascribe the equivalent of good deeds of the seven thousand years of the age of this world to the one who meets the need of any of his brothers in the faith on the path of Allah as if he spends his days in fasting and his nights in worship.(Al-Burhan fi Alamat al-Mahdi Akhir al-zaman, 88)
The Messenger of Allah (sallallahu alayhiwasallam) used comparisons to describe matters referring to the past, the future and the Hereafter.
The reference to 7,000 years here does not mean that the real age of the world is 7,000 years.
(Allah knows the truth) At that time, accounts regarding these 7,000 years may refer, like the start of a calendar, to the beginning of a very important event in human history, such as human beings establishing a settled life style after the flood and the life of this world restarting in a new form. In other words, the history of mankind may have restarted, people's numbers may have grown and urbanisation may have begun anew after that date. Some of the ulama have referred to the period following the Prophet Nuh (alayhis salaam) as a new beginning in the history of mankind. In the same way that Christians accept as if an important event took place 1987 years ago and divide history into dates before that time and dates after it, this account may well refer to a dating system based on events taking place prior to 7,000 years ago and events after. In other words, if the life of this world is 7,000 years, and if one says that "I am in a certain date of that period", then this person is referring to a specific way of calculating dates.
Imam Rabbani (radiAllahu anhu) related the following in his Letters.
Subsequently, 124,000 prophets came and went.(Letters of Rabbani, 1/354)
124,000 prophets came and went between the time of the Prophet Adam (alayhis salaam) and the Messenger of Allah (sallallahu `alayhi wa sallam). In another account Imam Rabbani (radi Allahu anhu) says:
The period of "1,000 years" that passed is the time up to the coming of a Ul'il Azm (great) prophet in past communities."(Letters of Rabbani, 1/495)
Generally speaking, a prophet came every 100 years and an Ul'il Azm prophet every 1000 years. If we agree that a prophet comes every 100 years, then from the time of the Prophet Adam (alayhis salaam) to the Messenger of Allah (sallallahu alayhi wa sallam):
124,000 x 100= 12,400,000 (years must have passed.) That means that in referring to the age of this world as 7,000 years, our Prophet (sallallahu alayhi wa sallam) is not speaking of its true age but of the date of the beginning of a most significant event. (Allah knows the truth.)
Ahmad Ibn Hanbal (radi Allahu anhu) says:
Five thousand, six hundred years have passed from this world. (Al-Burhan fi Alamat al-Mahdi Akhir al-zaman, 89)
Previous hadith have shown that the age of the world is 7,000 years. Reference is made to 5,600 years passing before our Prophet (sallallu alayhi wa sallam). According to that account, the life of the community of Prophet Muhammad (sallallhu alayhi wa sallam) extended until the year 1400 (Hegira calendar). (7,000-5,600=1,400)(Allah knows the truth)
Ahmad Ibn Hanbal (radi Allahu anhu) says:
Five thousand, six hundred years have passed from this world. (Al-Burhan fi Alamat al-Mahdi Akhir al-zaman, 89)
It has been related from Abdullah (radiAllahu anhu) that the Messenger of Allah (sallallahu alayhi wasallam) said: One of my people whose name is the same as mine will assume leadership... If but one day of life remains to the world, Allah will prolong that day to permit him to assume dominion. (Tirmidhi)
The blessed Ali (alayhis salaam) narrated that the Messenger of Allah (sallallahu alayhi wa sallam) said: Even if no more than a day remains until Doomsday, Allah will send an individual from my Ahl al-Bayt. (Abu Dawud)
Ibn al-Majah and Abu Naim relate an account from Abu Huraira (radi Allahu anhu), saying that the Prophet (sallallahu alayhi wa sallam) said: If only one day remains to the world Allah will prolong that day and make one from my Ahl al-Bayt lord.Al-Burhan fi Alamat al-Mahdi Akhir al-zaman, 10 Al-Qawl al-Mukhtasar fi Alamat al-Mahdi al- Muntadhar, 27 Death - Doomsday - The Hereafter and the Portents of the End Times, p. 437
As can be seen from various accounts and conditions, the year 1400 (according to the Hegira calendar) is also the year of the emergence of the Mahdi (`alayhis salaam). Even if only one day! remains until the year 1400, Doomsday will be postponed for a certain length of time to allow the Mahdi(`alayhis salaam), who is ready and waiting to serve, to do his duty. (Allah knows the truth.) Another trustworthy account from Ibn Abbas (radi Allahu anhu) cites the Prophet (sallallahu alayhi wa sallam) as saying: The world is seven days long, each day is like a thousand years, and the Messenger of Allah (sallallahu alayhi wa sallam) was sent at the end of that.
Zeid Al-Juhani narrated: I told the Messenger of Allah (sallallahu alayhi wa sallam) of a dream I had had. In that dream the Messenger of Allah (sallallahu alayhi wasallam) was at the top step of a seven-stepped pulpit. He said:The seven-stepped pulpit you see is the seven thousand years of the age of this world. I shall be in the last thousand of those years.'
(Al-Burhan fi 'Alamat al-Mahdi Akhir az-Zaman, 89)
Zeid Al-Juhani narrated: I told the Messenger of Allah (sallallahu alayhi wasallam) of a dream I had had. In that dream the Messenger of Allah (sallallahu alayhi wa sallam) was at the top step of a seven-stepped pulpit. He said:The seven-stepped pulpit you see is the seven thousand years of the age of this world. I shall be in the last thousand of those years.'
(Al-Burhan fi 'Alamat al-Mahdi Akhir az-Zaman, 89)
As can be seen from these accounts, the life span of the community extends up to 1400 (Hegira style). In 1400 (Hegira style), one day (i.e. one thousand years) will come to an end. Yet the community was still awaiting the coming of the blessed Mahdi on that day of closing. Therefore, that one day (one millennium) will be extended in such a way as to make the blessed Mahdi(`alayhis salaam)'s duties possible.
Imam Rabbani (radiAllahu anhu) reveals that the Mahdi will appear in the second millennium following the death of our Prophet (sallallahu alayhi wasallam):
"It is expected that, after 1,000 years, this secret administration will be renovated. It will be granted with superiority... This way, genuine virtue will emerge and cover the degradation... And it is expected that the Mahdi(`alayhis salaam), the supporter, will come. May Allah be pleased with him." (Imam Rabbani, Letters of Rabbani, vol. 1, p. 569)
The confirmation of the religious law, the renovation of people takes place in this second thousand. The just witnesses of the truthfulness of this cause are the existence of the Prophet Isa [alayhis salaam] and Mahdi(`alayhis salaam) in this period (the second thousand years). (Imam Rabbani, Letters of Rabbani, vol. 1, p. 611)
Those among the nation of Allah's Messenger (sallallahu alayhi wa sallam) are highly perfected in faith. It does not matter whether they are few in number, even a thousand years passes after the death of our Prophet (sallallahu alayhi wa sallam). Their being perfected in faith serves to the following end: strengthening the Islamic law in its true sense.The coming of the Mahdi(`alayhis salaam) after 1,000 years serves this purpose. Our Prophet (sallallahu alayhi wa sallam), the last Messenger, gave the glad tidings of his coming. The Prophet 'Isa (alayhis salaam), on the other hand, will come down after 1,000 years. (Imam Rabbani, Letters of Rabbani, vol. 1, p. 440)
A thousand years after our Prophet (sallallahu alayhi wa sallam), people will enter the second millennium. According to Imam Rabbani (radiAllahu anhu) , quoted above, the Mahdi(`alayhis salaam) and the Prophet 'Isa (alayhis salaam) will come during that time. The most appropriate time is between the years 1400 and 1600. These years fall in the exact middle of the second millennium. The prevalence of Islamic moral values is to be expected from 1400 to 1500, and degeneration and Doomsday between 1500 and 1600.
The life of this community will exceed 1,000 years, yet be limited to 1,500 years. (Muhammad ibn `Abd ar-Rasul Barzanji, Al-Isha`ah li Ashrat as-Sa`ah, p. 299) Beddiuzaman Said Nursi states that the life span of the community will be up until 1506.
Quoting from Jalal ad-Din as-Suyuti's book, Beddiuzaman Said Nursi states that the life span of the community will be up until 1506.
"The first statement, with reference to 1500, indicates the last times of those who struggle for religion in the End Times; the second statement, with reference to 1506 calls attention to the date of the victorious struggle. (...) until this date (1506), it hints that it will, evidently and clearly, continue in a victorious manner." (Sikke-i Tasdik-i Gayb, p. 46)
Some of the ulama, including Imam as-Suyuti(radiAllahu anhu) refer to the life of this community extending up to around 1500 (Hegira calendar), following which there will be a period of degeneration (Allah knows the truth). According to sahih hadith, the blessed Mahdi(`alayhis salaam) will live for 40 years after his appearance. It is also revealed in hadiths concerning the Prophet 'Isa (alayhis salaam) that he will remain on Earth some 40-45 years. the blessed Mahdi(`alayhis salaam) and the Prophet 'Isa (alayhis salaam) will live simultaneously of this mentioned time; for around 7-10 years. According to this information, the death of the blessed Mahdi and the Prophet 'Isa (alayhis salaam) will coincide with the years 1475-1480. There will be a period of 20-25 years, continuing up to 1500, when people try to preserve that legacy. It is also revealed in this account that the Mahdi will appear at the beginning of the century.
Yet his coming (of the blessed Mahdi(`alayhis salaam)) will take place at the beginning of the century. (Letters of Rabbani)
As stated above, according to Imam as-Suyuti's accounts, the life of the community of Prophet Muhammad (sallallahu alayhi wasallam) will not exceed the year 1500. The beginning of only one century remained before the year 1500 (Hegira), that of 1400.
The Messenger of Allah (sallallahu alayhi wa alihi wa sallam) said: Doomsday will not take place until a century in which Allah is not worshipped has passed. (Al-Burhan fi Alamat al-Mahdi Akhir al-Zaman, p. 92)
In the light of the above accounts, we may expect a century of happiness followed by a century in which oppression and denial prevail, followed by Doomsday. The calculations will be confirmed when the Mahdi(`alayhis salaam) appears at the beginning of the 1400s. Since the life span of the community will not exceed the year 1500 (Hegira), the Mahdi(`alayhis salaam) should appear in the early 1400s.(Al-Qawl al-Mukhtasar fi Alamat al-Mahdi al- MuntadharAl-Burhan fi Alamat al-Mahdi Akhir al-Zaman) (Life-Death-The Hereafter and the Portents of the End Times, 494) (Ramuz al-Ahadith 508 (Ibn Majah-al-Tabarani in al-Kabir) )Shaykh `AbdulQadir Jilaaniy (radi Allahu `anhu) said:"IMAM MAHDI WILL BE BORN IN 1400 HIJRI (1980-81)"(Book: Tazkira Anwaar e Sabiri 3rd Edition Page 143. Haqiqat e Gulzaar e Sabri)According to this saying, Imam Mahdi (alayhis salaam) is 34 years old uptill now, and he will appear at the age of 40 at the Kaaba Shareef according to Hadith Shareef (Tabarani, Al mujam alkabir)The above prediction is exactly what Hadith Shareef said, that Imam Mahdi (alayhis salaam) will be born in the begining of a century. you can read this above.