The uncle of 'Abbaad bin Tamim, 'Abdullah bin Zayd Radiyallahu 'Anhu reports:
"I have seen Rasulullah Sallallahu 'Alayhi Wasallam lying flat on his back in the masjid, with one leg resting on the other. (IT)
English reference (IT): Book 20, Hadith 121 (IT)
Arabic reference (IT): Book 21, Hadith 128 (IT)