Is it permissible to place the Mushaf on the ground for prostration when reciting an verse that contains a prostration, or must it be raised to an elevated place?

There is no harm in placing the Mus'haf (Qur'an) on a pure ground when prostrating for recitation (sajdat at-tilawah). However, if it is possible to place it in a raised position or hand it to someone next to you, that would be better, out of reverence for it and to avoid any misgivings.