Bulugh al-Maram, Book 3, Hadith 604 (English)

Jabir (RAA) narrated that the Messenger of Allah prohibited whitening a grave with plaster, to sit on it or to build over it (such as a dome).’ Related by Muslim.

وَلِمُسْلِمٍ عَنْهُ: { نَهَى رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-أَنْ يُجَصَّصَ الْقَبْرُ, وَأَنْ يُقْعَدَ عَلَيْهِ, وَأَنْ يُبْنَى عَلَيْهِ } 1‏.‏ ‏1 ‏- صحيح.‏ رواه مسلم (970)‏.‏

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also referenced under: Book 3, Hadith 48 (In-Book)