The following excerpt is taken from ‘islamqa.info’:
Praise be to Allaah.
The word “soor” (translated here as trumpet) means a horn, like a trumpet or bugle. The Messenger of Allaah (peace and blessings of Allaah be upon him) was asked about the Trumpet and he explained it in terms of what the Arabs knew in their own language, as narrated in Sunan al-Tirmidhi (3244) and elsewhere from ‘Abd-Allaah ibn ‘Umar (may Allaah be pleased with him) who said: A Bedouin said: “O Messenger of Allaah, what is the Trumpet?’ He said: “A horn that is blown into.” Classed as saheeh by al-Albaani in al-Saheehah, 1080.
With regard to the one who will blow into it, it is well known that he is Israafeel (peace be upon him). Some of the scholars narrated that there is consensus on this, and it is stated clearly in some ahaadeeth. See Fath al-Baari, 11/368.
The Messenger (peace and blessings of Allaah be upon him) has told us that the one who will blow the Trumpet has been ready to do so since Allaah created him, as it is narrated in al-Mustadrak from Abu Hurayrah (may Allaah be pleased with him), who said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “The gaze of the one who will blow the Trumpet has been fixed since he was entrusted with it, looking towards the throne, ready (to blow it), in case he will be commanded to do so before he blinks, as if his eyes are two shining stars.” Classed as saheeh by al-Albaani in al-Silsilah al-Saheehah, 1078.
The majority of scholars are of the view that the Trumpet will be blown twice: the first time all creatures will swoon and the second time the resurrection will come to pass. This is based on the verse in which Allaah says (interpretation of the meaning):
“And the Trumpet will be blown, and all who are in the heavens and all who are on the earth will swoon away, except him whom Allaah wills. Then it will be blown a second time, and behold they will be standing, looking on (waiting)”
And it is based on the saheeh ahaadeeth which mention these two blowings and what will follow them. al-Bukhaari (4651) and Muslim (2955) narrated that Abu Hurayrah said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Between the two blowings of the Trumpet there will be forty.” The people said, “O Abu Hurayrah! Forty days?” I said: “I am not sure.” They said, “Forty years?” I said: “I am not sure.” They said, “Forty months?” I said: “I am not sure. Then Allaah will send rain down from the sky and they will grow as herbs grow. There is no part of a man which will not decay except a single bone at the base of the coccyx, from which he will be re-created on the Day of Resurrection.”
Al-Nawawi said: what is meant by the words of Abu Hurayrah, “I am not sure” is that he could not be certain as to whether what was meant was forty days or years or months; all that he was certain of was that it was forty in general terms.
In Saheeh Muslim (2940) it is narrated that ‘Abd-Allaah ibn ‘Amr (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “… then the Trumpet will be blown and no one will hear it but he will bend his neck to one side and raise it from the other side. The first one who will hear it will be a man who is busy in setting right the cistern meant for supplyingwater to the camels. He will swoon and the other peoplewill also swoon. Then Allah will send or He will send down rain which will be like dew and there will grow outof it the bodies of people. Then the trumpetwill be blown again, and they will stand up and begin to look around.”
Some of the scholars said that the trumpet will be blown three times, including the time when it will be blown and all people will be terrified, which will come before the people swoon. … They based this on the verse in which Allaah says (interpretation of the meaning):
“And (remember) the Day on which the Trumpet will be blown, and all who are in the heavens and all who are on the earth, will be terrified except him whom Allaah will (exempt). And all shall come to Him, humbled”
But the fact that swooning is mentioned in one verse and terror is mentioned in another does not mean that they will not happen at the same time when the Trumpet is blown for the first time. Rather they will happen at the same time, so when the Trumpet is blown the people will be terrified, and will swoon as a result and die.
They also quoted as evidence some ahaadeeth in which it is mentioned that the Trumpet will be blown three times.
But the hadeeth which they quote as evidence is the lengthy hadeeth about the Trumpet, which is a da’eef (weak) hadeeth, as al-Haafiz ibn Hajar (may Allaah have mercy on him) said. And Allaah knows best. See al-Tadhkirah by al-Qurtubi (184); Fath al-Baari, 11/369.
From the above it may be understood that when Allaah decrees that all living beings should die, He will command the angel to blow the Trumpet, so he will give a mighty blast which will terrify all creatures, as a result of which they will swoon and die. Then they will stay like that for as long as Allaah decrees, which is described as forty without specifying whether that is years, months or days – Allaah knows best how long it is. Their bodies will decay within this period until there is nothing left but the bone from the base of the coccyx, which is a round bone at the base of the spine. Then Allaah will send a cloud that will release rain, and when the water reaches this bone, the body will grow from it like a plant grows and they will be recreated from this bone, just as Allaah created them the first time, for He is able to do all things. Then he will blow the Trumpet to signal the Resurrection, and the souls will return to their bodies and will come forth from their graves and hasten to the place of gathering. We ask Allaah for His mercy and kindness.
What the Muslim has to do is to prepare for these decisive moments by hastening to do righteous deeds and keeping away from evil things and bad deeds.
If the one who most feared Allaah said, “How can Ibe at ease when the one who blows the trumpet hasput it to his mouth, bent hisforehead and inclined his ear, waiting to see when he will be ordered toblow it?” – as narrated by al-Tirmidhi in al-Sunan, 243, and others, and classed as saheeh by al-Albaani in al-Silsilah, 1079 – then what about us who are weak and fall short? We ask Allaah to make us among those who will not be grieved by the greatest terror when the angels will meet them (with the greeting), “This is your Day which you were promised.” (cf. al-Anbiya’ 21:103). And Allaah knows best.
See al-Qiyaamah al-Kubra by Shaykh ‘Umar al-Ashqar, 33-42; A’laam al-Sunnah al-Manshoorah, 122.