The Messenger of Allah ﷺ forbade plastering graves with gypsum, sitting on them, or building structures over them.
نهى رسول الله ﷺ أن يجصص القبر، وأن يقعد عليه، وأن يبنى عليه.
Muslim narrated it in the Book of Funerals (970) through several routes from Ibn Jurayj, who said, "Abu Zubayr told me that he heard Jabir bin Abdullah." He then related the hadith, which has already been mentioned a few chapters earlier.