The ruling on writing on the Grave of the Deceased
Question :
Is it permissible to place a piece of iron or a sign upon the grave of the deceased that has Verses of the Qur'an written on it along with the name of the deceased person and the date that he died, etc.?
Answer:
It is not permissible to write on the grave of the deceased, neither the Verses of the Qur'an nor anything else. No writing should be done, whether it is on iron, on a sign or anything other than them. This is due to what is confirmed from the Prophet in a Hadith related from Jabir that he (the Prophet) prohibited plastering the grave, sitting on it and building structures over it. This was recorded by Muslim. At- Tirmithi and An-Nasa'i both added in their versions with an authentic chain of narration: "and that he (the Prophet) prohibited that it be written on."
Source:
Ash-Shaykh Ibn Baz
Fatawa Islamiyah, Vol. 3 Page 84