Contracting marriage at a graveyard

Q 1: A person believes that the dead can bring about harm and benefits and thus, has concluded his marriage in a shrine. Is this marriage valid?

A: If they believe that the person buried in the shrine brings about good to the marriage contracts that are concluded there, blesses the couple in their marital life, and brings them happiness, they are Mushriks (persons who associate others with Allah in His Divinity or worship) and their marriage contracts take the same ruling on those of Kafirs (disbelievers), regarding parentage, inheritance, and the like. Such contracts are valid if the couple embrace Islam and sincerely believe in Tawhid (the Oneness of Allah). May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.