وَسُؤَالُ مُنْكَرٍ وَنَكِيرٍ، وَهُمَا مَلَكَانِ يَدْخُلَانِ الْقَبْرَ
There is questioning by Munkar and Nakir, two angels who enter the grave.
Questioning in the grave means that angels question the deceased during this intermediate state. Their action belongs to the unseen realm and therefore cannot be made dependent solely on what ordinary observers can watch.
The essential point is the occurrence and transmitted basis of the questioning, not an invented description of the angels' appearance or voice. Reports differ in subsidiary details; the central affirmation and every incidental narrative detail should not be treated as having exactly the same evidentiary standing.