حَدَّثَنَا إِسْحَاقُ بْنُ مُوسَى قَالَ: حَدَّثَنَا مَعْنٌ قَالَ: حَدَّثَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ: «أَنَّ رَسُولَ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ كَانَ يُصَلِّي مِنَ اللَّيْلِ إِحْدَى عَشْرَةَ رَكْعَةً يُوتِرُ مِنْهَا بِوَاحِدَةٍ، فَإِذَا فَرَغَ مِنْهَا اضْطَجَعَ عَلَى شِقِّهِ الْأَيْمَنِ»
Umm al-Mu'mineen Sayyidah Aisha Siddiqa (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) used to offer eleven rak'ahs of prayer at night, one of which was Witr. Then, when he finished, he would lie down on his right side.