Shaykh Muhammad Salih al-Munajjid says:
“Islam forbids erecting structures over graves, and commands that any such structures should be knocked down. But it is permitted to put a marker on the grave so that the family and friends of the deceased will know where it is (and nothing more than this). However, this marker should not be a structure or anything else that is not allowed in sharee’ah.”
With regard to the prohibition on erecting structures over graves, it was narrated that Jabir said: “The Messenger of Allah forbade plastering over graves, sitting on them and erecting structures over them.” (Sahih Muslim, 970)
Al-Shawkani said:
“The phrase ‘erecting structures over them’ indicates that it is Haram to build anything over a grave.”
Al-Shafi’i said:
“I saw the imams in Makkah ordering that what had been built (over graves) was to be knocked down.”
Shaykh Muhammad Salih al-Munajjid says:
“With regard to the command to knock down structures that have been built over graves, that is proven in the Sunnah.”
It was narrated that Abu’l-Hayaaj al-Asadi said: Ali ibn Abi Talib said to me: “Shall I not send you on the same mission as the Messenger of Allah sent me? Do not leave any statue without erasing it, and do not leave any raised grave without leveling it.” (Sahih Muslim, 969).
Al-Shawkani said:
“The words ‘do not leave any raised grave without leveling it’ means that the Sunnah is that a grave should not be made very high, and there should be no differentiation between those who were virtuous and those who were not virtuous.”
Shaykh Muhammad Salih al-Munajjid says:
“Making a grave higher than the amount that is permitted is Haram…The making graves high that is mentioned in the Hadith especially includes the domes and shrines that are built over graves, and the taking of graves as places of worship. The Prophet cursed those who do that (refer to Nayl al-Awtaar, 4/130).”