On the recommendation to lie down on the right side after the two rak'ats of Fajr

Riyad as-Salihin (The Meadows of the Righteous)

by Imam Nawawi

198. Chapter: On the recommendation to lie down on the right side after the two rak'ats of Fajr and encouraging doing that whether or not one has prayed voluntary prayers in the night

1110. 'A'isha said, "After the Prophet, may Allah bless him and grant him peace, prayed the two rak'ats of Fajr, he would lie down on his right side." [al-Bukhari]

1111. 'A'isha said, "Between the time he finished the 'Isha' prayer until Fajr, the Prophet, may Allah bless him and grant him peace, used to pray eleven rak'ats, and he would say the salam after every two rak'ats and perform the witr with one. When the mu'adhdhin fell silent after calling the Fajr prayer and the time of Fajr was clear and the mu'adhdhin had come to him, he would do two quick rak'ats and then lie down on his right side until the mu'adhdhin came to him for the iqama." [Muslim]

1112. Abu Hurayra reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "When one of you has prayed the two rak'ats of Fajr, he should lie down on his right side." [Abu Dawud and at-Tirmidhi]