"The Messenger of Allah ﷺ used to pray eleven rak'ahs at night between finishing Isha' prayer and Fajr, apart from the two rak'ahs of Fajr, and he would prostrate for as long as it takes one of you to recite fifty verses. (Using translation from Nasāʾī 1749)
كَانَ رَسُولُ اللهِ ﷺ «يُصَلِّي إِحْدَى عَشْرَةَ رَكْعَةً فِيمَا بَيْنَ أَنْ يَفْرُغَ مِنْ صَلَاةِ الْعِشَاءِ إِلَى الْفَجْرِ بِاللَّيْلِ سِوَى رَكْعَتَيِ الْفَجْرِ وَيَسْجُدُ قَدْرَ مَا يَقْرَأُ أَحَدُكُمْ خَمْسِينَ آيَةً»
"The Messenger of Allah ﷺ used to pray eleven rak'ahs, making it odd (witr) by one between the time when he finished 'Isha and dawn, and he would prostrate for as long as it takes one of you to recite fifty verses before raising his head."
عَائِشَةُ كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي فِيمَا بَيْنَ أَنْ يَفْرُغَ مِنْ صَلاَةِ الْعِشَاءِ إِلَى الْفَجْرِ إِحْدَى عَشْرَةَ رَكْعَةً وَيُوتِرُ بِوَاحِدَةٍ وَيَسْجُدُ سَجْدَةً قَدْرَ مَا يَقْرَأُ أَحَدُكُمْ خَمْسِينَ آيَةً قَبْلَ أَنْ يَرْفَعَ رَأْسَهُ وَبَعْضُهُمْ يَزِيدُ عَلَى بَعْضٍ فِي الْحَدِيثِ مُخْتَصَرٌ
"The Messenger of Allah ﷺ used to pray eleven rak'ahs at night between finishing Isha' prayer and Fajr, apart from the two rak'ahs of Fajr, and he would prostrate for as long as it takes one of you to recite fifty verses.
كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي إِحْدَى عَشْرَةَ رَكْعَةً فِيمَا بَيْنَ أَنْ يَفْرُغَ مِنْ صَلاَةِ الْعِشَاءِ إِلَى الْفَجْرِ بِاللَّيْلِ سِوَى رَكْعَتَىِ الْفَجْرِ وَيَسْجُدُ قَدْرَ مَا يَقْرَأُ أَحَدُكُمْ خَمْسِينَ آيَةً