Graves are not a place for answering Du`a' (supplication) - Allamah Ibn Baaz
Preventing Du`a' at the graves
From `Abdul-`Aziz ibn `Abdullah ibn Baz to the dear brother, may Allah guide you! Amen. As-salamu `alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you!)
We received your letter dated 3/3/1974, may Allah guide you, and we already know the information included therein. May Allah bless your marriage. You asked us in your letter to supplicate to Allah for you at the grave of the Messenger (peace be upon him).
Please be advised that it is not permissible to supplicate at the graves, whether it is the grave of the Prophet (peace be upon him) or anyone else. Graves are not a place for answering Du`a' (supplication); it is only permissible to visit them, greet the dead, supplicate to Allah for them, and remember death and the Hereafter.
We would like to remind you of this so that you are well-informed. You can refer to the Hadith of visiting the graves in the end of the chapter of funerals in the book entitled "Bulugh Al-Maram" in order to make sure of this.
May Allah guide you and us to follow the Sunnah (whatever is reported from the Prophet) and to act according to what pleases Allah (Glorified be He) and draws us closer to His religion.
As-salamu `alaykum warahmatullah wabarakatuh.
President of the Islamic University in Madinah
Ibn Baz Fatwas>Volume 6>Preventing Dua at the graves