A person turning over onto his face in a dream indicates associating partners with God the Exalted and losing this world and the hereafter. If he turns over from his face onto his back, he will repent to God the Exalted, and it indicates his facing people [openly]. Lying face-down indicates illnesses of the abdomen. If the dreamer is a woman, she will turn away from her husband.
Dream meaning · al-Nabulsi
Falling (turning over) on one's face انقلاب الإنسان
Source: al-Nabulsi, Ta'tir al-Anam fi Ta'bir al-Manam, p. 22. English translation by iDreamBot. Quran verses: Quran.com, Saheeh International.