"When the Muaddhin fell silent after the Adhan for the beginning of Fajr, he would pray two brief rak'ahs, then he would lie down on his right side." (Using translation from Nasāʾī 1762)  

كَانَ رَسُولُ اللهِ ﷺ إِذَا سَكَتَ الْمُؤَذِّنُ بِالْأُولَى مِنْ صَلَاةِ الْفَجْرِ «قَامَ فَرَكَعَ رَكْعَتَيْنِ خَفِيفَتَيْنِ قَبْلَ صَلَاةِ الْفَجْرِ بَعْدَ أَنْ يَتَبَيَّنَ الْفَجْرُ ثُمَّ يَضْطَجِعُ عَلَى شِقِّهِ الْأَيْمِنِ»