Musnad Abu Ya'la al-Mawsili 42:47

Al-Abbas ibn al-Walid al-Narsi narrated to us, Wahib narrated to us, Abd al-Rahman ibn Yazid ibn Jabir narrated to us, from al-Qasim ibn Mukhaymirah, from Abu Sa’id, who said: The Prophet of Allah, may Allah bless him and grant him peace, forbade that one should build upon graves, or sit upon them, or pray upon them.