رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 1767
The Book of the Prohibited actions
Prohibition of Plastering and Building over the Graves
عَنْ جَابِرٍ رَضِيَ اللَّه عَنْهُ قَالَ: نَهَى رَسُولُ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ أَنْ يُجَصَّصَ الْقَبْرُ، وَأَنْ يُقْعَدَ عَلَيْهِ، وَأَنْ يُبْنَى عَلَيْهِ. ((رَوَاهُ مُسْلِم))
Jabir (May Allah be pleased with him) said: The Messenger of Allah (ﷺ) forbade that the graves should be plastered (made into permanent structures), used as sitting places (for the people) or building over them. [Muslim].
Riyad as-Salihin, 1767