وعن عائشة رضى الله عنها
قالت: كان النبي صلى الله عليه وسلم يصلى من الليل إحدى عشرا ركعة، فإذا طلع الفجر صلى ركعتين خفيفتين، ثم اضطجع على شقه الأيمن حتى يجئ المؤذن فيؤذنه
The Prophet (sallallahu alayhi wa sallam) used to offer eleven Rakah of optional Salat (prayers) in the latter part of night. When it was about dawn, he would offer two short Rakah and then would lie down on his right side till the Muadhdhin (one who calls for prayer) would come to inform him that the congregation had gathered (for prayer).
Riyad as-Salihin 815, Book 5, The Book of the Etiquette of Sleeping, Lying and Sitting etc, Hadith 3. 1 min read