Images of the blessings of the grave
Question

Who are pious what happens to them in their grave?.
Praise be to Allah.The evidence indicates that the believer will be blessed in his grave until the Hour begins, then he will move by the grace and mercy of Allaah to the blessings that will never cease or come to an end, which is the blessing of Paradise. May Allaah make us among its people. 
These are some of the images of the blessings which are bestowed upon the believer in his grave: 
1-His grave is furnished from Paradise for him
2-He is clothed in garments from Paradise.
3-A gate to Paradise is opened for him, and its breezes come to him, and he smells its fragrance and he feels delight in what he can see of its blessings.
4-His grave is made wide and spacious for him.
5-He is given the glad tidings of Allaah’s pleasure and Paradise. Hence he longs for the Hour to begin. 
It was narrated that al-Bara’ ibn ‘Aazib said: “We went out with the Messenger of Allaah (peace and blessings of Allaah be upon him) for the funeral of a man from among the Ansaar. We came to the grave and when (the deceased) was placed in the lahd, the Messenger of Allaah (peace and blessings of Allaah be upon him) sat down and we sat around him, as if there were birds on our heads (i.e., quiet and still). In his hand he had a stick with which he was scratching the ground. Then he raised his head and said, “Seek refuge with Allaah from the torment of the grave”, two or three times. Then he said, “When the believing slave is about to depart this world and enter the Hereafter, there come down to him from heaven angels with white faces like the sun, and they sit around him as far as the eye can see. They bring with them shrouds from Paradise and perfumes from Paradise. Then the Angel of Death comes and sits by his head, and he says, ‘O good soul, come forth to forgiveness from Allaah and His pleasure.’ Then it comes out easily like a drop of water from the mouth of a waterskin. When he seizes it, they do not leave it in his hand for an instant before they take it and put it in that shroud with that perfume, and there comes from it a fragrance like the finest musk on the face of the earth. Then they ascend and they do not pass by any group of angels but they say, ‘Who is this good soul?’ and they say, ‘It is So and so the son of So and so, calling him by the best names by which he was known in this world, until they reach the lowest heaven. They ask for it to be opened to them and it is opened, and (the soul) is welcomed and accompanied to the next heaven by those who are closest to Allaah, until they reach the seventh heaven. Then Allaah says: ‘Record the book of My slave in ‘Illiyoon in the seventh heaven, and return him to the earth, for from it I created them, to it I will return them and from it I will bring them forth once again.’ So his soul is returned to his body and there come to him two angels who make him sit up and they say to him, ‘Who is your Lord?’ He says, ‘Allaah.’ They say, ‘What is your religion?’ He says, ‘My religion is Islam.’ They say, ‘Who is this man who was sent among you?’ He says, ‘He is the Messenger of Allaah (peace and blessings of Allaah be upon him).’ They say, ‘What did you do?’ He says, ‘I read the Book of Allaah and I believed in it.’ Then a voice calls out from heaven, ‘My slave has spoken the truth, so prepare for him a bed from Paradise and clothe him from Paradise, and open for him a gate to Paradise.’ Then there comes to him some of its fragrance, and his grave is made wide, as far as he can see. Then there comes to him a man with a handsome face and handsome clothes, and a good fragrance, who says, ‘Receive the glad tidings that will bring you joy this day.’ He says, ‘Who are you? Your face is a face which brings glad tidings.’ He says, ‘I am your righteous deeds.’ He says, ‘O Lord, hasten the Hour so that I may return to my family and my wealth.’…” 
Narrated by Ahmad, 17803; Abu Dawood, 4753. Classed as saheeh by al-Albaani in Ahkaam al-Janaa’iz, p. 156 
6-He will be happy when he sees what would have been his place in Hell, which Allaah has replaced for him with a place in Paradise. 
Ahmad (10577) narrated that Abu Sa’eed al-Khudri said: I attended a funeral with the Messenger of Allaah (peace and blessings of Allaah be upon him). The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “O people, this ummah will be tested in their graves. When a man is buried and his friends leave him, an angel with a hammer in his hand comes and sits by him and asks, ‘What do you say about this man?’ If he is a believer, he says, ‘I bear witness that there is no god but Allaah and that Muhammad is His slave and Messenger.’ He says, ‘You have spoken the truth.’ Then a door to Hell is opened for him and he says, ‘This would have been your place if you had disbelieved in your Lord, but because you believed, this is your place.’ Then a door to Paradise is opened for him and he wants to go there, but the angel says to him, ‘Calm down,’ and his grave is made wide and spacious for him. But if he is a kaafir or a hypocrite, (the angel) says to him, ‘What do you say about this man?’ He says, ‘I do not know, I heard the people saying something.’ The angel says, ‘You did not know and you did not follow those who knew and you were not guided.’ Then a door to Paradise is opened for him and he says, ‘This would have been your position if you had believed in your Lord. But because you disbelieved, Allaah has replaced it for you with this.’ Then a gate to Hell is opened for him, and he strikes him a blow with the hammer which is heard by all of Allaah’s creation apart from the two races (of mankind and the jinn).” Some of the people said, “O Messenger of Allaah, there is no one who would have an angel standing by him holding a hammer but he would dumbfounded.” The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Allaah will keep firm those who believe, with the word that stands firm.” [Ibraaheem 14:27 – interpretation of the meaning]
Classed as saheeh by al-Albaani in his commentary on Kitaab al-Sunnah by Ibn Abi ‘Aasim, 865 
7-He will sleep the sleep of a bridegroom
8-His grave will be illuminated for him
It was narrated that Abu Hurayrah said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “When the deceased (or he said: any one of you) is buried, two black and blue angels, one of whom is called Munkar and the other Nakeer come to him. They say, ‘What did you say about this man?’ And he says what he used to say, that he is the slave of Allaah and His Messenger, ‘I bear witness that there is no god but Allaah and that Muhammad is His slave and Messenger.’ They say, ‘We knew that you would say this.’ Then his grave is expanded, seventy cubits wide, and it is filled with light. He says, ‘Let me go back to my family and tell them.’ They say, ‘Sleep like a bridegroom whom no one will wake but his most beloved,’ until Allaah raises him up. But if he was a hypocrite he says, ‘I heard the people saying something and I said likewise, I do not know.’ So they say, ‘We knew that you would say that.’ Then it is said to the earth, ‘Squeeze him,’ so it squeezes him until his ribs interlock. And he will remain like that, being tormented, until Allaah raises him up.” 
Narrated by al-Tirmidhi, 1071. Classed as saheeh by Shaykh al-Albaani in al-Silsilah al-Saheehah, 1391. 
With regard to his sleep being likened to the sleep of a bridegroom, that is because he will be so happy and comfortable.  Tuhfat al-Ahwadhi. 
These are some of the blessings that the believer will enjoy in his grave. We ask Allaah to make us among His people. 
And Allaah knows best.