The exact time of (al-Sa'at al'Uzma (the Great Hour), or Day of Doom, is known only to God.

Anas ibn Malik told this Hadith (reported by Ibn Majh and Bukhari) spoken by the Prophet: "I shall tell you a Hadith which I heard from the Messenger of Allah, and which no one will tell you after me. I heard him say, 'Among the signs of the Hour will be the disappearance of knowledge and the appearance of ignorance. Adultery will be prevalent and the drinking of wine will be common. The number of men will decrease and the number of women will increase until there will be fifty women to be looked after by one man.'"

Ali ibn Abi Talib quotes the Prophet (pboh) thus: "The Hour will come when leaders are oppressors, when people believe in the stars and reject al-Qadar [Divine Decree, prophecy] when a trust becomes a way of making a profit, when people give to charity reluctantly, when adultery becomes widespread --- when this happens, then your people will perish.'"

As recorded by Bukhari, Abu Hurairah reported that the Prophet (saws) said: "The Hour will not come until the following events have come to pass: people will compete with one another in constructing high buildings; two big groups will fight one another, and there will be many casualties --- they will both be following the same religious teaching; earthquakes will increase; time will pass quickly; afflictions and killing will increase; nearly thirty dajjals will appear, each of them claiming to be a messenger from Allah; a man will pass by a grave and say, 'Would that I were in your place'; the Sun will rise from the West; when it rises and the people see it, they will all believe, but that will be the time when 'No good will it do to a soul to believe in them then, if it believed not before'; and a wealthy man will worry lest no one accept his Zakat [charity]."

Some exegetes claim that the rising of the Sun in the West refers to the rise of Islam in Europe, but it more likely indicates a shift of the Earth's axis, which is predicted by several prophets of other cultures.

Abu Sa'id al-Khudri states that the Prophet (saws) said: "Thunderbolts will increase so much as the Hour approaches that when a man comes to a people, he will ask, 'Who amongst you was struck by a thunderbolt this morning?' and they will say, 'So-and-so and so-and-so was struck'."

Abu Hurairah recorded that the Prophet (saws) said: "The Hour will not come until there has been rain which will destroy all dwellings except tents."

Ibn Majah narrated this Hadith: "The Prophet said: Just before the Hour, there will be days in which knowledge will disappear and ignorance will appear, and there will be much Harj" [killing in the Ethiopian language; also quoted by Bukhari in Volume 9, Book 88, Numbers 183, 185 &186, narrated Abu Musa)

In like wise, according to Bukhari, Abu Hurairah (radiallahu anhu) said: "The Prophet said, Time will pass rapidly, knowledge will decrease, miserliness will become widespread in peoples hearts, afflictions will appear, and there will be much Harj. The people asked, O Messenger of Allah, what is Harj? He said, Killing, killing!"

Ahmad recorded a report by Abd Allah ibn 'Amr, that the Prophet (saws) said: "The Hour will not come until Allah takes away the best people on earth; only the worst people will be left; they will not know any good or forbid any evil."

Ahmad also quotes Mohammed (pboh) via Alba'al-Salami, thus: "I heard the Prophet (saws) say: 'The Hour will only come upon the worst of the people'."

The Sahih of Al-Bukhari transmits this warning from Mohammed (pboh): "The least of the signs of the Last Hour will be a fire which will gather mankind together from the East and West... Finally, a cold wind will come and kill all believers, leaving only unbelievers on the earth who will then witness the Last Hour. The angel Israfil will blow a trumpet, and the resurrection of all human beings will begin...

"The Hour will come suddenly: when a man has milked his she-camel and taken away the milk, but he will not have time to drink it; before a man repairing a tank for his livestock will be able to put water in it for his animals; and before a man who has raised a morsel of food to his mouth will be able to eat it."

Mohammed (pboh) speaks of the Day of Doom, thus in Quran 56: "Say: The ancients, and the later folk shall be gathered at the appointed time of a known day. Then you erring ones, you that cried lies, you shall eat of a tree called Zakkoum, and you shall fill therewith your bellies and drink on top of that boiling water, lapping it down like thirsty camels. This shall be their hospitality on the Day of Doom."

"So, when the Trumpet is blown with a single blast and the earth and the mountains are lifted up and crushed with a single blow, then, on that day, the Terror shall come to pass, and heaven shall be split, for upon that day it shall be very frail, and the angels shall stand upon its borders, and upon that day eight shall carry above them the throne of the Lord. On that day you shall be exposed, not one secret of yours concealed..." (Quran 69)

Another version of the Trumpet prophecy states that, at the first sounding everyone will be struck with terror, at the second blast, all will be struck down, and all will be resurrected at the third. The Qur'an emphatically describes two trumpet blasts, which have been interpreted to represent two Resurrections:

"And there shall be a blast on the Trumpet, and all who are in the Heaven and all who are on the earth shall expire, save those whom God shall vouchsafe to live. Then there shall be another blast on it, and lo! Arising they shall gaze around them: and the earth shall shine with the light of her Lord." (Qur'an 39: 68-69)

"One day, the disturbing trumpet blast shall disturb it which the second blast shall follow. Verily, it will be but a single blast." (Qur'an 79: 6, 7, 13)

Amen