Virtues of the Prayer Hall (Sutra of the Musalla)
Bukhari :: Book 1 :: Volume 9 :: Hadith 492
Narrated 'Aisha:
the wife of the Prophet, "I used to sleep in front of Allah's Apostle with my legs opposite his Qibla (facing him); and whenever he prostrated, he pushed my feet and I withdrew them and whenever he stood, I stretched them." 'Aisha added, "In those days there were no lamps in the houses."