There is no need to delay the burial of somebody as there are many Prophetic hadiths that state that it is a Sunnah to hasten the burial of the dead.
Sheikh Muhammad ibn Al-Mukhtar Ash-Shanqiti, President of the Islamic Association of Lubbock, Texas, US, states the following: The Prophet (peace and blessings be upon him) taught us to bury the deceased immediately. Any condition causing the delay such as last visit might be done after burial, when the deceased is in his or her grave. And even if one does this, this should not be the last one, as every Muslim is asked to visit the graves of their loved ones and make du’aa` for them whenever he is able to. The only case in which the burial might be delayed is when we have a legal issue related to death, e.g., if there is some sort of investigation to be done or the identity of the deceased must be established in case of mutilation.
Moreover, Dr. Wahbah Az-Zuhayli, head of the Department of Fiqh at Faculty of Shari`ah, Damascus University, states the following: It is makruh (reprehensible) to delay the burial of the dead, as the Prophet (peace and blessings be upon him) is reported to have said, “Hasten the burial of the dead ones amongst you. If he is a righteous person, then it will be good for him to hasten the burial. If it is the other way, then you will be free from an evil placed on your shoulders.” I would like to stress here that the custom that is prevalent in some countries when they delay the burial of the dead has no place in the Shari`ah, as it stands in contradiction with the Prophetic Sunnah as clarified above.
It has become clear now that delaying the burial of the dead is a reprehensible act unless there is a religiously acceptable reason for such delay, as clarified by Sheikh Ash-Shanqiti above.