Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.076A.

The jurists differ concerning the legality of reciting the Qur’an by the graveside. Ash-Shafi’i and Muhammad bin Al-Hasan consider it desirable, because by it, the deceased might be blessed. Al-Qadi ‘Iyad and scholars of the Maliki school agree with them on this point. Ahmad holds that there is nothing wrong in reciting the Qur’an at a grave, whereas Malik and Abu Hanifah view this as not desirable because the sunnah does not mention this practice.