Graves
The Prophet Muhammad (Peace be upon him) forbade that graves be plastered over and buildings be erected over them.
Among the prohibited are:
路 Erecting walls around the graves as is common nowadays.
路 Cementing or casting concrete on the surface of the grave.
路 Placing marble stones or other fancy decorative material at the grave as is the custom of Non-Muslims.
路 Placing stones with writing or inscriptions of any kind, be these verses of the holy Qur’an or Poetry, etc.
路 Placing flowers on the graves.
(Awake to the call of Islam Vol. 4. No 4. Page 34 )