Primarily, we hasten to bury the dead because of the specific instructions of the Prophet (peace and blessings be upon him) in this respect. Prior to their death, the true believers are given glad tidings. On the other hand, those who are wicked are also given tidings of the impending chastisement awaiting them.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: It is a true that a soul may be given intimations of its final destiny prior to the person’s death. We are told in the Qur’an: (Those who say; “Our Lord is Allah,” then remain steadfast, the angels shall descend on them, (saying): “Fear not, nor grieve, but rejoice in the
good news of the Garden that has been promised to you. We are your protecting friends in this life and in the Hereafter. There you will have whatever you desire, and whatever you request.”) (Fussilat 41:30-31)
According to the Qur’an commentators, this is a reference to the glad tidings given to the true believers prior to their death. On the other hand, those who are wicked will also be given tidings of the impending chastisement awaiting them.
Although, why do we hasten to bury the dead, let me state: We are doing so primarily because of the specific instructions of the Prophet (peace and blessings be upon him) in this respect. He is reported to have said, “(Once death has been ascertained) hasten with the funeral rites (including the burial): if the person is good then you are certainly hastening him to his final resting place which is all good for him; if he on the other hand is wicked, then you are any way relieving yourself by doing so.” (Reported by Al-Bukhari and Muslim) `Ali, the fourth caliph, is also reported to have said, “One of the three things we must not delay is burying the dead after performing the required funeral rites without any undue delay.”
In such matters, we are best advised to shun all personal opinions and abide by the guidance of the Lawgiver. We are told in the Qur’an that the Prophet (peace and blessings be upon him) while speaking on such matters is doing so not based on his own personal whims but solely based on the inspiration given to him.