Lead me to her (or his) grave. They led him to that place and he said prayer over her (or him) and then remarked: Verily, these graves are full of darkness for their dwellers. Verily, the Mighty and Glorious Allah illuminates them for their occupants by reason of my prayer over them.
The Book of Prayer - Funerals
Sahih Muslim 956
Hadith Commentary
This narration demonstrates the profound spiritual status of the Prophet Muhammad (peace be upon him) and the efficacy of his supplications. When he prayed over a grave, Allah would illuminate that dark abode for its inhabitant through the barakah (blessing) of the Prophet's prayer.
The graves are described as places of darkness, which refers to the isolation and constriction experienced in the barzakh (intermediate realm between death and resurrection). The illumination mentioned is both literal - actual light filling the grave - and metaphorical, representing divine mercy, comfort, and protection from punishment.
This hadith emphasizes the importance of visiting graves and offering prayers for the deceased, particularly when performed by righteous individuals whose supplications are more likely to be accepted. It also teaches us about the Prophet's compassion and concern for his ummah, even after their death.
Juridical Rulings
Scholars derive from this that praying at gravesites is permissible, though the prayer should be for mercy and forgiveness rather than directed to the deceased.
The practice of seeking righteous people to pray for the deceased is established through this narration, as their prayers may bring divine mercy to the departed.
This hadith does not indicate that one should specifically seek the Prophet's grave for prayer after his death, as his unique status cannot be replicated by others.