The Ruling on Building over Graves

Question:

What is the ruling of the religion on building graves with bricks and cement, above the surface of the earth?

Answer:

First of all, I dislike for a person to be addressed by such questions as: "What is the ruling of the religion, or what is the ruling of Islam," or such like, because one person cannot speak for Islam, for he might be mistaken, or he might be right. So if we say that a person speaks for Islam, it amounts to saying that he is never wrong, since there are no mistakes in Islam. It is therefore better to say, in such cases: "What do you consider is the ruling on one who does such and such?" or: "What is your opinion regarding one who does such and such?" or: "What is your view in Islam, is the ruling for such and such?" The important thing is that the question be worded in a way that reflects the real worth of the one being questioned.

As for my view regarding this question, then it is not allowed to build over graves. This is because it is confirmed that the Prophet forbade building over graves, plastering the grave, or that something be erected over it. So the structure over the grave is prohibited since it is a means toward using it for worship and committing Shirk with Allah the Almighty, the Majestic.

Source:
Ibn 'Uthaimin.
Fatawa Islamiyah, Vol. 1 Pages 231-232