Ibn Tikhfah al-Ghifari said: My father told me that the Messenger of Allah (peace and blessings be upon him) hosted him as a guest along with a few people, and they spent the night at his (peace and blessings be upon him) home. Then the Messenger of Allah (peace and blessings be upon him) went out during the night and found him lying on his stomach. He (peace and blessings be upon him) nudged him with his foot and woke him, then said: "Do not lie like this, for this is the way the people of Hell lie."
Hadith Referenceالمعجم الكبير للطبراني / باب الطاء / 8195