The Saudi House of Fatwa issued the following: “The punishment and the bliss in the grave, and the questioning of the two angels are among the issues that Ahl As-Sunnah wal Jama`ah (the mainstream Muslims) have unanimously agreed upon. This is based on some evidences from the Qur’an and the authentic Sunnah of the Prophet (peace and blessings be upon him).
The evidences from the Qur’an are as follows:
1- Allah Almighty says: “While a dreadful doom encompassed Pharaoh’s folk.‏The Fire; they are exposed to it morning and evening; and on the day when the Hour upriseth (it is said): Cause Pharaoh’s folk to enter the most awful doom.” (Ghafir: 45-46) This verse explicitly proves the existence of punishment in the grave before the Day of Judgment.
2- Allah Almighty says: “Thou could see, when the wrong doers reach the pangs of death and the angels stretch their hands out, saying: Deliver up your souls. This day ye are awarded doom of degradation for that ye spoke concerning Allah other than the truth, and scorned, His portents.” (Al-An`am: 93) This is an address to the wrong doers while they are dying, informing them that they would be severely tormented on that very day of their death. If the punishment were to be postponed to the Day of Judgment, they would not have been told: “This day ye are awarded”. This proves that there is a torment in the grave.
3- Allah Almighty says: “And verily, for those who do wrong, there is a punishment beyond that. But most of them know not.” (At-Tur: 47) This verse apparently indicates that the first punishment is that in the grave, for it would be incorrect to interpret it as referring to the punishment in this life because many wrong doers are not punished during their lifetime.
4- Allah Almighty says: “And We shall chastise them twice; then they will be relegated to a painful doom.” (At-Tawbah: 101) The first torment in the verse refers to the punishment in life and the second one refers to the torment of the grave. Allah then says: “Then they will be relegated to a painful doom…”, which refers to the torment of the Hereafter.
the evidences from the Sunnah are more explicit and detailed. Here are some examples:
1- It is reported in the two Sahihs (authentic collections of hadiths) of Al-Bukhari and Muslim that the Prophet (peace and blessings be upon him) once passed by two graves and said: “These two persons are being tortured but not for a major sin (to avoid). One of them never saved himself from being soiled with his urine, while the other used to go about with calumnies (to make enmity between friends).”
2- It is reported in the Sahih of Muslim that the Prophet (peace and blessings be upon him) said: “It has been revealed to me that you people will be put to trial nearly like the trial of Ad-Dajjal (antichrist), in your graves. If it were not for the reason that you would stop burying (your dead) in the graves on listening to the torment in the grave which I am listening to, I would have certainly made you hear that.”
3- It is reported also in the Sahih of Muslim that the Prophet (peace and blessings be upon him) said: “When any one of you completes the last Tashahhud, he should seek refuge with Allah from four (trials): the torment of Hell, the torment of grave, the trial of life and death, and the evil of the trial of al-Masikh Ad-Dajjaal (Antichrist).”
It is worth stressing here that all these hadiths are authentic and related from the Prophet (peace and blessings be upon him) with a continuous chain of reliable transmitters and whoever does not believe in what they say is in a great danger. The Sheikh of Islam, Ibn Taymiyyah, is quoted as saying: ‘There are many authentic hadiths that prove the existence of the punishment and the bliss in the grave to whoever deserves them, and also the questioning of the two angels in the grave.’
therefore, every one has to repose faith in these things without asking about the way they take place because this is beyond man’s comprehension.”