Sheikh `Atiyya Saqr, former Head of Al-Azhar Fatwa Committee, states the following: “Al-Bukhari narrates on the authority of Ibn `Abbas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) once passed by two graves and said, “These two persons are being tortured 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).” The Prophet (peace and blessings be upon him) then took a green leaf of a date-palm tree, split it into (pieces) and fixed one on each grave. They said, “O Allah’s Messenger! Why have you done so?” He replied, “I hope that their punishment might be lessened till these (the pieces of the leaf) become dry.”
In his book Sharh Sunan Abi Dawud (vol. 1, p.42), Al-Khattabi maintains that no one, save the Prophet (peace and blessings be upon him) is given the privilege to place a palm leaf on the grave as a means of intercession to lessen the torture inflicted on the deceased. At-Tartushi, a Shafi`i scholar, makes it clear that only the Prophet’s blessed hand could do such an act, and it is not for Muslims in general.
However, Al-Khattabi maintains that the lessening of the torture was due to the Prophet’s invocation on behalf of the deceased, and that it has nothing to do with dry or soft leaves.
Moreover, Al-Qadi `Iyad also supports the aforementioned view and states that putting those date-palm leaves on the grave is based on knowing the condition of the deceased buried therein, and this is part of the Unseen, not revealed to anyone. The Prophet’s remarks: “Now they are being tortured,” indicates that he knew their condition and this is unique to being a Prophet. Besides, such a matter was not a common practice among the Companions to indicate that they adopted it as a permissible action. In fact, none of them did so except Buraydah ibn al-Khasib al-Aslami.
On the other hand, some scholars maintain that such action is permissible for all. This is based on their assumption that there is no evidence indicating that this matter is part of the Prophet’s prerogatives. There is also no evidence showing that the Prophet’s Companions were against the action of Ibn al-Khasib al-Aslami, who ordered his family upon his death to put two date-palm leaves on his grave.
In short, this is a debatable issue. But, I think that it is permissible as long as one has a strong belief that only Almighty Allah has the power of benefiting or inflicting harm upon one, and as long as what we do is just a means of seeking Allah’s mercy and forgiveness for the deceased. There is no need to consider it unlawful.”