Sahih al-Bukhari, Hadith 475 ⓘ
Narrated `Abbad bin Tamim: that his uncle said, "I saw Allah's Messenger lying flat (on his back) in the mosque with one leg on the other." Narrated Sa`id bin Al-Musaiyab that `Umar and `Uthman used to do the same.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عَبَّادِ بْنِ تَمِيمٍ، عَنْ عَمِّهِ، أَنَّهُ رَأَى رَسُولَ اللَّهِ صلى الله عليه وسلم مُسْتَلْقِيًا فِي الْمَسْجِدِ، وَاضِعًا إِحْدَى رِجْلَيْهِ عَلَى الأُخْرَى. وَعَنِ ابْنِ شِهَابٍ عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ قَالَ كَانَ عُمَرُ وَعُثْمَانُ يَفْعَلاَنِ ذَلِكَ.
also referenced under: Book 8, Hadith 123 (In-Book) & Volume 1, Book 8, Hadith 464 (USC-MSA)