Messenger of Allah ﷺ used to pray two light rakʿat before the morning (compulsory) prayer after the day dawned and the Mu'adh-dhin had finished his Adhan. He then would lie on his right side till the Mu'adh-dhin came to pronounce the Iqama.  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا سَكَتَ الْمُؤَذِّنُ بِالأُولَى مِنْ صَلاَةِ الْفَجْرِ قَامَ فَرَكَعَ رَكْعَتَيْنِ خَفِيفَتَيْنِ قَبْلَ صَلاَةِ الْفَجْرِ بَعْدَ أَنْ يَسْتَبِينَ الْفَجْرُ ثُمَّ اضْطَجَعَ عَلَى شِقِّهِ الأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ لِلإِقَامَةِ  

"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."  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا سَكَتَ الْمُؤَذِّنُ بِالأُولَى مِنْ صَلاَةِ الْفَجْرِ قَامَ فَرَكَعَ رَكْعَتَيْنِ خَفِيفَتَيْنِ قَبْلَ صَلاَةِ الْفَجْرِ بَعْدَ أَنْ يَتَبَيَّنَ الْفَجْرُ ثُمَّ يَضْطَجِعُ عَلَى شِقِّهِ الأَيْمَنِ  

[Machine] The Messenger of Allah ﷺ used to pray eleven units of prayer during the night. When the dawn came, he would pray two quick units of prayer, then lie down on his right side until the Mu'adhin calls him for prayer.  

كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي مِنَ اللَّيْلِ إِحْدَى عَشْرَةَ رَكْعَةً فَإِذَا فَجَرَ الْفَجْرُ صَلَّى رَكْعَتَيْنِ خَفِيفَتَيْنِ ثُمَّ اتَّكَأَ عَلَىشِقِّهِ الْأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ يُؤْذِنُهُ لِلصَّلَاةِ  

[Machine] When the Mu'adhin finished calling the Adhan, the Messenger of Allah ﷺ used to pray two brief Rak'ahs, then lay down on his right side until the Mu'adhin came to inform him to start the prayer.  

كَانَ رَسُولُ اللهِ ﷺ إِذَا ثَوَّبَ الْمُؤَذِّنُ صَلَّىرَكْعَتَيْنِ خَفِيفَتَيْنِ ثُمَّ اضْطَجَعَ عَلَى شِقِّهِ الْأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ فَيُؤْذِنَهُ بِالصَّلَاةِ  

[Machine] The Messenger of Allah ﷺ used to pray eleven rak'ahs between the completion of 'Isha prayer, which is when people are called to the darkness of dawn, and the dawn prayer. In each set of two rak'ahs, he would recite the salaam. Additionally, he would perform one witr rak'ah. When the muezzin finished calling for the dawn prayer and the dawn appeared to him, and the muezzin came to him, he would stand and perform two light rak'ahs, then lie down on his right side until the muezzin came to him with the call to establish the prayer.  

«كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي فِيمَا بَيْنَ أَنْ يَفْرُغَ مِنْ صَلَاةِ الْعِشَاءِ وَهِيَ الَّتِي يَدْعُو النَّاسُ الْعَتَمَةَ إِلَى الْفَجْرِ إِحْدَى عَشْرَةَ رَكْعَةً يُسَلِّمُ فِي كُلِّ رَكْعَتَيْنِ وَيُوتِرُ بِوَاحِدَةٍ فَإِذَا سَكَتَ الْمُؤَذِّنُ مِنْ صَلَاةِ الْفَجْرِ وَتَبَيَّنَ لَهُ الْفَجْرُ وَجَاءَهُ الْمُؤَذِّنُ قَامَ فَرَكَعَ رَكْعَتَيْنِ خَفِيفَتَيْنِ وَاضْطَجَعَ عَلَى شِقِّهِ الْأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ بِالْإِقَامَةِ»  

"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»