Musnad Ahmad 329:15

Hajjaj ibn Muhammad narrated to us, from Ibn Jurayj, who said: Yahya ibn Jurjah informed me, from Ibn Shihab, from 'Abbad ibn Tamim, from his uncle, that he saw the Messenger of Allah (peace and blessings of Allah be upon him) lying on his back in the mosque, placing one of his legs over the other.