Abu Marthad Kannaz bin Husain (May Allah be pleased with him) said:
I heard the Messenger of Allah (ﷺ) saying: "Do not offer Salat (prayer) facing the graves and do not sit on them."[Muslim]. (IT)
App reference (IT): Book 18, Hadith 247 (IT)
Arabic/English book reference (IT): Book 18, Hadith 1757 (IT)