(5) باب الضَّجْعِ عَلَى الشِّقِّ الأَيْمَنِ
Narrated Aisha:
The Prophet (ﷺ) used to pray eleven rak`at in the late part of the night, and when dawn appeared, he would offer two rak`at and then lie on his right side till the Muadhdhin came to inform him (that the morning prayer was due).
Reference: Sahih al-Bukhari 6310
In-book reference: Book 80, Hadith 7
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 75, Hadith 322