Sunan Ibn Majah
1198
Hasan Sahih+3

It was narrated that ‘Aishah said:“When the Prophet (ﷺ) prayed the two (Sunnah) Rak’ah of Fajr, he would lie down on his right side.”

Hasan SahihAl-Albani
Hasan SahihMuhammad Fouad Abd al-Baqi