A man was praying at a grave, and another man came and did not pray with him, but prayed alone at the same grave. What is the ruling on their prayers?

Question:
He says: Honorable Shaykh, may Allah grant you success, a man was praying at a grave, and another man came and did not want to pray with him, so he prayed alone at the same grave. Is this permissible?

Answer:
This prayer is invalid. Prayer at graves is prohibited by authentic hadiths, because this is a means to shirk (associating partners with Allah). The prayer is invalid because it is prohibited. Also, if one prays at a grave, this involves desecrating the grave and harming the deceased. The Prophet (peace and blessings be upon him) prohibited sitting on graves, placing things on them, or causing them harm. If one prays on a grave, he does not tread on it, although the act of praying at graves or on them is prohibited. His prayer is invalid because it is a prohibited prayer, and prohibition implies invalidity. This is a means to shirk. Yes.