What is the ruling of Islamic law on giving advice and admonition to the deceased?

The ruling on a will varies according to its circumstances among the four schools of thought. It can be obligatory if a person has a legal right that he fears will be lost, such as a trust, a debt, or zakat. It can be recommended if one bequeaths a portion of his wealth to non-inheriting relatives, the poor, or for charitable assistance. It can be forbidden if it leads to harm to the heirs, as the Prophet, peace and blessings be upon him, said: "Indeed, a man may do the deeds of the people of good for seventy years, then when he makes his will, he acts unjustly in it, so his worst deed is sealed for him, and he enters the Fire." It is advisable to prepare and document the will, as the Prophet, peace and blessings be upon him, said: "It is not right for a Muslim man who has anything to bequeath to sleep for two or three nights, except that his will is written with him."