Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) forbade that structures be built over graves, that one sit on them, or that prayer be offered on them. (Allamah al-Haythami says:) I say: Ibn Majah recorded only the part prohibiting building over a grave.
Abu Ya'la recorded it; its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجنائز / 4320