What is the wisdom behind the Prophet (peace be upon him) placing two palm branches on two graves whose occupants were being tormented, in order to alleviate their suffering, and is it legislated for us to do the same?

It has been authentically reported that the Prophet, peace and blessings be upon him, passed by two graves whose occupants were being tormented. One was being tormented because of backbiting (namimah (definition)), and the other for not concealing himself from urine. So, he (peace and blessings be upon him) planted a fresh palm branch on each grave and said, "Perhaps their torment will be lightened as long as they do not dry out."

There are differing opinions regarding the reason for the alleviation of the torment: 1. It was said that the two fresh branches would glorify Allah (tasbih) as long as they did not dry out, and tasbih alleviates torment. This is weak because everything glorifies Allah. 2. The more probable explanation is that the Prophet, peace and blessings be upon him, hoped from Allah that He would lighten their torment for the duration that the two branches remained fresh, as a warning to the Ummah against these two great sins.

It is not permissible to place palm branches or trees on graves with the intention of alleviating torment from the deceased for several reasons: 1. It has not been revealed to us that the deceased is being tormented, unlike the Prophet, peace and blessings be upon him, who received revelation. 2. It involves having a bad assumption about the deceased, as they might be in bliss or have been forgiven. 3. This was not part of the guidance of the righteous predecessors (Salaf al-Salih). 4. There is something better than this, which is to seek forgiveness for the deceased and ask Allah to grant them steadfastness.