When someone dies, his personal yaum-al-qiyamah (Day of Judgement) has started. In fact, the recompense starts at the time of death itself. For the believer, who is waiting to meet his Lord Almighty, he is eager to leave this world; he leaves this world with high state of emaan we say, and as he dies, the angels welcome him and give him glad tidings, SubhanAllah.
Prophet Sallallahu alihiwassalam said: “…when the time of the death of a believer approaches, he receives the good news of God’s pleasure with him and His blessings upon him, and so at that time nothing is dearer to him than what lies ahead of him. He therefore loves meeting God, and God loves meeting him.” (Sahih Al-Bukhari)
For the one who disbelieved, and was disobedient to Allah SWT, he dreads meeting with his Lord, and knows it is not going to bring good to him. Prophet Sallallahu alihi wassalam warned us: “When the time of the death of a disbeliever approaches, he receives the evil news of God’s torment and His Requital, whereupon nothing is more hateful to him than what is before him. Therefore, he hates the meeting with God, and God too, hates the meeting with him.” (Sahih Al-Bukhari)
As death approaches the wicked disbeliever, he is made to feel something of the heat of the Hellfire. This taste of what is to come causes him to plead for a second chance on earth to do the good he knew he should have done. The evil soul leaves the body with great difficulty, drawn out by the angels as a thronged skewer is dragged through wet wool.
Allah says in the Qur'an:
حَتَّى إِذَا جَآءَ أَحَدَهُمُ الْمَوْتُ قَالَ رَبِّ ارْجِعُونِ - لَعَلِّى أَعْمَلُ صَـلِحاً فِيمَا تَرَكْتُ كَلاَّ إِنَّهَا كَلِمَةٌ هُوَ قَآئِلُهَا وَمِن وَرَآئِهِمْ بَرْزَخٌ إِلَى يَوْمِ يُبْعَثُونَ
Allah SWT says:
وَلَوْ تَرَى إِذْ يَتَوَفَّى الَّذِينَ كَفَرُواْ الْمَلَـئِكَةُ يَضْرِبُونَ وُجُوهَهُمْ وَأَدْبَـرَهُمْ وَذُوقُواْ عَذَابَ الْحَرِيقِ
The true believer and the righteous, the one who will be accepted into Jannah, will have his grave roomy and spacious and filled with light. He is shown what would have been his abode in Hell - had he been a wicked sinner - before a portal is opened for him every morning and evening showing him his actual home in Paradise. He will have a blissful journey and the angels will be waiting to welcome him in the heavens. Allah SWT says:
إِنَّ الَّذِينَ قَالُواْ رَبُّنَا اللَّهُ ثُمَّ اسْتَقَـمُواْ تَتَنَزَّلُ عَلَيْهِمُ الْمَلَـئِكَةُ أَلاَّ تَخَافُواْ وَلاَ تَحْزَنُواْ وَأَبْشِرُواْ بِالْجَنَّةِ الَّتِى كُنتُمْ تُوعَدُونَ - نَحْنُ أَوْلِيَآؤُكُمْ فِى الْحَيَوةِ الدُّنْيَا وَفِى الاٌّخِرَةِ وَلَكُمْ فِيهَا مَا تَشْتَهِى أَنفُسُكُمْ وَلَكُمْ فِيهَا مَا تَدَّعُونَ - نُزُلاً مِّنْ غَفُورٍ رَّحِيمٍ
Verily, those who say: "Our Lord is Allah,'' and then they stand firm, on them the angels will descend (saying): "Fear not, nor grieve! But receive the glad tidings of Paradise which you have been promised! We have been your friends in the life of this world and are (so) in the Hereafter. Therein you shall have (all) that your souls desire, and therein you shall have (all) for which you ask. An entertainment from the Oft-Forgiving, Most Merciful.'' (Surah Al-Fussilat: 30-32)
However, for the doomed, his experience in the grave will be a torturous one. The floor of his grave is set alight with some of Hell’s fierce fire, and his grave is made narrow and constricted to the extent that his ribs become intertwined as his body is crushed. Then, an incredibly ugly being, wearing ugly garments and giving off a foul and offensive odor comes to the disbelieving soul and says: “Be grieved with what displeases you, for this is your day which you have been promised.” The disbeliever will ask: “Who are you, with your face so ugly and bringing evil?” The ugly one will reply: “I am your wicked deeds!” The disbeliever is then made to taste bitter remorse as he is shown what would have been his abode in Paradise - had he lived a righteous life - before a portal is opened for him every morning and evening showing him his actual home in Hell. Allah mentions in His Book how the wicked people of Pharaoh are, at this very moment, suffering from such an exposure to Hell from within their graves:
النَّارُ يُعْرَضُونَ عَلَيْهَا غُدُوّاً وَعَشِيّاً وَيَوْمَ تَقُومُ السَّاعَةُ أَدْخِلُواْ ءَالَ فِرْعَوْنَ أَشَدَّ الْعَذَابِ
The Fire, they are exposed to it, morning and afternoon. And on the Day when the Hour will be established (it will be said to the angels): "Admit Fir`awn's people into the severest torment!'' (Surah Al-Ghaafir: 46)
Zaid Ibn Thaabit Radhiyallahu anh narrates that when the Prophet Muhammad and his Companions were once passing some graves of polytheists, the Prophet’s horse bolted and almost unseated him. The Prophet Sallallahu alihiwassalam then said:“These people are being tortured in their graves, and were it not that you would stop burying your dead, I would ask God to let you hear the punishment in the grave which I (and this horse) can hear.” (Sahih Muslim)
May Allah SWT always guide us on the Sirathul Musthaqueem, and grant us high positions in Jannathul Firdaws. May He save us from the torment of the grave and the Hell-fire, aameen.
And Allah knows best.