(27) باب فِي صَلاَةِ اللَّيْلِ
Narrated 'Aishah, wife of Prophet (ﷺ):
The Messenger of Allah (ﷺ) used to pray eleven rak'ahs (at night, observing the witr with one rak'ahs). When he finished it (the prayer), he would lie down on his right side.
Reference: Sunan Abi Dawud 1335
In-book reference: Book 5, Hadith 86
English translation: Book 5, Hadith 1330