It wasnarrated that 'Aishah said:
"When the Prophet (ﷺ) prayed thetwo (Sunnah) Rak'ah of Fajr, he would lie down on his right side." (TR)
English reference (TR): Vol. 1, Book 5, Hadith 1198 (TR)
Arabic reference (TR): Book 5, Hadith 1254 (TR)