The Messenger of Allah ﷺ used to pray witr with three rak'ahs. In the first he would recite: "Glorify the Name of Your Lord, the Most High" in the second: "Say: O you disbelievers!", and in the third: "Say: He is Allah, (the) One". And he would say the Qunut before bowing, and when he finished he would say: Subhanal-Malikil-Quddus (Glory be to the Sovereign, the Most Holy) three times, elongating the words the last time.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُوتِرُ بِثَلاَثِ رَكَعَاتٍ كَانَ يَقْرَأُ فِي الأُولَى بِ { سَبِّحِ اسْمَ رَبِّكَ الأَعْلَى } وَفِي الثَّانِيَةِ بِ { قُلْ يَا أَيُّهَا الْكَافِرُونَ } وَفِي الثَّالِثَةِ بِ { قُلْ هُوَ اللَّهُ أَحَدٌ } وَيَقْنُتُ قَبْلَ الرُّكُوعِ فَإِذَا فَرَغَ قَالَ عِنْدَ فَرَاغِهِ سُبْحَانَ الْمَلِكِ الْقُدُّوسِ ثَلاَثَ مَرَّاتٍ يُطِيلُ فِي آخِرِهِنَّ  

"In the first rak'ah of witr, the Messenger of Allah ﷺ used to recite: "GLorify the Name of your Lord, the Most High;" in the second; "Say: O you disbelievers!" and in the third; "Say: He is Allah, (the) One."  

كَانَ رَسُولُ اللَّهِ ﷺ يَقْرَأُ فِي الرَّكْعَةِ الأُولَى مِنَ الْوَتْرِ بِ { سَبِّحِ اسْمَ رَبِّكَ الأَعْلَى } وَفِي الثَّانِيَةِ بِ { قُلْ يَا أَيُّهَا الْكَافِرُونَ } وَفِي الثَّالِثَةِ بِ { قُلْ هُوَ اللَّهُ أَحَدٌ }  

"The Messenger of Allah ﷺ used to recite: "Glorify the Name of Your Lord, the Most High;" in witr, in the second rak'ah he would recite: "Say: O you disbelievers!"; and in the third "Say: He is Allah, (the) One". And he only said the taslim at the end, and he would say- meaning after the taslim: Subhanal-Malikil-Quddus (Glory be to the Sovereign, the Most Holy)' three times."  

كَانَ رَسُولُ اللَّهِ ﷺ يَقْرَأُ فِي الْوَتْرِ بِ { سَبِّحِ اسْمَ رَبِّكَ الأَعْلَى } وَفِي الرَّكْعَةِ الثَّانِيَةِ بِ { قُلْ يَا أَيُّهَا الْكَافِرُونَ } وَفِي الثَّالِثَةِ بِ { قُلْ هُوَ اللَّهُ أَحَدٌ } وَلاَ يُسَلِّمُ إِلاَّ فِي آخِرِهِنَّ وَيَقُولُ يَعْنِي بَعْدَ التَّسْلِيمِ سُبْحَانَ الْمَلِكِ الْقُدُّوسِ ثَلاَثًا