Everyone has to die one day. Allah says in the Quran:

“Everyone is going to taste death, and We shall make a trial of you with evil and with good, and to Us you will be returned.” Quran (Surah Al-Anbiya:21)

However, the return of every soul to the afterlife shall depend on its state of righteousness in this world. To the pious believers, it will be said (as stated in the Quran):

27. (It will be said to the pious): “O (you) the one in (complete) rest and satisfaction!.
28. “Come back to your Lord well-pleased (yourself) and well-pleasing (unto Him)!.
29. “Enter you then among My (honored) slaves,.
30. “And enter you My Paradise!”

Ibn Abi Hatim recorded from Ibn `Abbas concerning Allah’s statement in verses 27 and 28 above that this verse was revealed while Abu Bakr was sitting (with the Prophet). So he said, `O Messenger of Allah! There is nothing better than this!’ The Prophet then replied,

(This will indeed be said to you.)”

In another detailed hadith stated below, the Messenger of Allah (S) describes the details of how a soul of a believing and righteous person is welcomed in the next world.

Upon the authority of al-Bara’ ibn `Aazib who said: We went out with the Prophet (S) to a burial of a man from the Ansaar (original inhabitants of Madina) until we arrived at the grave and he still had not been placed in the slot of the grave.

Then the Messenger of Allah (S) sat down and we sat around him. You would have thought that birds were upon our heads from our silence and in the hand of the Messenger of Allah (S) was a stick which he was poking the ground with. Then he started looking at the sky and looking at the earth and looking up down three times. Then he said to us: “Ask Allah for refuge from the torment of the grave“, he repeated this command two or three times. Then he said O Allah I seek refuge in you from the torment of the grave (three times).  He then said,

‘When the believer is about to depart from this world and go forward into the Next World, angels with faces as bright as the sun descend from the heavens and sit around him in throngs stretching as far as the eye can see. Then the Angel of Death comes and sits at his head and says, “Good soul, come out to forgiveness and pleasure from Allah!” Then his soul emerges like a drop of water flows from a water-skin and the angel takes hold of it. When he has grasped it, the other angels do not leave it in his hand even for the twinkling of an eye. They take it and place it in a perfumed shroud and a fragrance issues from it like the sweetest scent of musk found on the face on the earth.
‘Then they bear it upwards and whenever they take it past a company of angels, they ask,”Who is this good soul?” and the angels with the soul reply, “So-and-so the son of so-and-so,” using the best names by which people used to call him in this world. They bring him to the lowest heaven and ask for the gate to be opened for him. It is opened for him and angels who are near Allah from each of the heavens accompany him to the subsequent heaven until he reaches to the heaven where Allah the Great is. Allah, the Mighty and Majestic,says,’Register the book of My slave in ‘Illiyun and take him back to earth. I created them from it and I return them to it and I will bring them forth from it again.”

‘His soul is then returned to his body and two angels come to him. They make him sit up and say to him, “Who is your Lord?” He replies, “My Lord is Allah.”They ask him, “What is your religion?”He replies, “My religion is Islam.” They ask him, “Who is this man who was sent among you?” He replies, ”The Messenger of Allah.” They ask him, “How did you come to know these things?” He replies, “I read the Book of Allah, believed it, and declared it to be true.” Then a Voice from on high declares, “My slave has spoken the truth, so spread out carpets from the Garden for him and open a gate of the Garden for him!” Then some of its fragrance and perfume comes to him, his grave is expanded for him as far as the eye can see, and a man with beautiful garments and a fragrant scent comes to him and says, “Rejoice in what delights you for this is the day which you were promised.” He asks, “Who are you? Yours is a face which presages good.” He replies, “I am your good actions.” Then he (the soul) says, “O Lord, let the Last Hour come soon so that I may rejoin my family and my property!”

The above is part of a long hadith that continues to describe the opposite that happens with the wrongdoers in this world with whom Allah is not happy because they don’t believe in the principles of Tawhid and refute His commands.

Regarding the illiyun described in the hadith where Allah says, ‘Register the book of My slave in ‘Illiyun and take him back to earth. I created them from it and I return them to it and I will bring them forth from it again’, the Quran describes it in these verses:

19. And what will make you know what ‘Illiyyun is?.
20. A Register inscribed,.
21. To which bear witness those nearest (to Allah, i.e. the angels).