ENOfficial
'Abbad ibn Tamim reported: His paternal uncle said that he saw the Prophet (Allah bless him and give him peace) lying on his back in the mosque, placing one of his legs over the other.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا سَعِيدُ بْنُ عَبْدِ الرَّحْمَنِ الْمَخْزُومِيُّ، وَغَيْرُ وَاحِدٍ، قَالُوا: حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ عَبَّادِ بْنِ تَمِيمٍ، عَنْ عَمِّهِ، أَنَّهُ رَأَى النَّبِيَّ صلى الله عليه وسلم مُسْتَلْقِيًا فِي الْمَسْجِدِ وَاضِعًا إِحْدَى رِجْلَيْهِ عَلَى الأُخْرَى.
sunnah.com