Musannaf Ibn Abi Shaybah

Hazrat Thumamah bin Shufay says that during the era of Hazrat Muawiyah, we set out from this city for a military expedition (battle), and Hazrat Fadala bin Ubaid was with us. His cousin Hazrat Nafi’ passed away. Hazrat Fadala stood with us at his grave. When we had buried him, he said: “Make his grave level and even, for indeed the Messenger of Allah (peace and blessings be upon him) commanded that graves be leveled.”

Hazrat Abdullah bin Sharhabil narrates that Hazrat Usman came out and ordered the leveling of graves: we leveled all the graves except the grave of Umm Amr bint Usman. He asked, "Whose grave is this?" People replied, "It is the grave of Umm Amr." He ordered that it too be leveled, so it was also leveled.

Hazrat Hanish Al-Kinani narrates that a soldier came to Hazrat Ali (may Allah be pleased with him), and he said to him, "Go, do not leave any belongings except that you pick them up, and do not leave any grave without leveling it." He called him back and asked, "Do you know for what task I have sent you? I have sent you for the same task for which the Messenger of Allah (peace and blessings be upon him) sent me."

The servant of Hazrat Ibn Abbas (may Allah be pleased with them both) narrates: Hazrat Abdullah bin Abbas (may Allah be pleased with them both) said to me: When you see a people who, after burying the dead, make a grave that is not like the graves of the Muslims, then make it equal to the graves of the Muslims.

Hazrat Abu Majliz says that leveling the graves is from the Sunnah.

The same is narrated from Hazrat Abu Majliz.

Hazrat Mansur bin Abdur Rahman narrates that a person asked Hazrat Imam Shabi, "A man buried his deceased and made the grave level with the ground (is this correct?)" He replied, "I have seen the graves of the martyrs of Uhud; they are raised above the ground."