Hearts that are discerned with the truth and reality and are outside the essence of nature and facing just the material world and feel that their shadow is also like themselves.
They are not on right path because left out of the straightness and facing nature and material world which is of the lowest degree.
Perhaps in that world hereafter, some of them will have to will walk with their faces while their feet upwards and some will walk on their bellies and some will walk there with hands and feet, like animals.
Citing this verse from the holy Quran "then is one who walks fallen on his face.." says
These parables are of metaphorical nature but could be turn as a reality and embodied in the world hereafter.
(An exposition on Forty Hadith, pp. 532-533)
http://en.imam-khomeini.ir/en/n51891/The-Supplication-for-the-3th-Day-of-Ramadan