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. (Using translation from Nasāʾī 1699)  

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُوتِرُ بِثَلَاثِ رَكَعَاتٍ يَقْرَأُ فِي الْأُولَى بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَفِي الثَّانِيَةِ بِقُلْ يَا أَيُّهَا الْكَافِرُونَ وَفِي الثَّالِثَةِ بِقُلْ هُوَ اللهُ أَحَدٌ وَيَقْنُتُ قَبْلَ الرُّكُوعِ فإِذَا فَرَغَ قَالَ عِنْدَ فَرَاغِهِ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» ثَلَاثَ مَرَّاتٍ يُطِيلُ فِي آخِرِهِنَّ  

The Messenger of Allah ﷺ used to recite in witr: "Glorify the Name of Your Lord, the Most High;' and "Say: O you disbelievers!'; and 'Say: He is Allah, (the) One." And after he had said the salam, he would say: Subhanal-Malikil-Quddus (Glory be to the Sovereign, the Most Holy) raising his voice the third time." (Using translation from Nasāʾī 1750)  

عَنْ أَبِيهِ كَانَ رَسُولُ اللهِ ﷺ يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ وَيَقُولُ بَعْدَمَا يُسَلِّمُ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» ثَلَاثَ مَرَّاتٍ يَرْفَعُ بِهَا صَوْتَهُ  

Ubayy bin Ka'b said: "The Messenger of Allah ﷺ used to recite in Witr: "Glorify the Name of your Lord, the Most High;" and "Say: O you disbelievers!;' and 'Say: He is Allah, (the) One.' And when he said the salam, he would say: Subhanal-Malikil-Quddus (Glory be to the Sovereign, the Most Holy) three times." (Using translation from Nasāʾī 1729)   

كَانَ رَسُولُ اللهِ ﷺ يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ فَإِذَا أَرَادَ أَنْ يَنْصَرِفَ قَالَ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» ثَلَاثًا يَرْفَعُ بِهَا صَوْتَهُ