۞ أَفَلَا يَعْلَمُ إِذَا بُعْثِرَ مَا فِى ٱلْقُبُورِ ۝٩ What is the role of مَا after passive بُعْثِرَ?

Surah Al-‘Adiyat — Part 2

• Deputy subject
• Accusative object
• Negative particle
• Time adverb