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 فَإِذَا فَرَغَ قَالَ عِنْدَ فَرَاغِهِ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» ثَلَاثَ مَرَّاتٍ يُطِيلُ فِي آخِرِهِنَّ قَالَ أَبُو عَبْدُ الرَّحْمَنِ وَقَدْ رَوَى هَذَا الْحَدِيثَ غَيْرُ وَاحِدٍ عَنْ زُبَيْدٍ فَلَمْ يَذْكُرْ أَحَدٌ مِنْهُمْ فِيهِ «ويقْنُتُ قَبْلَ الرُّكُوعِ»  

“The Messenger of Allah ﷺ used to perform Witr and recite: ‘Glorify the Name of your Lord the Most High.’, [Al-A’la (87)] ‘Say: O you disbelievers!” [Al-Kafirun (109)] and ‘Say: Allah is One.”. [Al-Ikhlas (112)] (Using translation from Ibn Mājah 1171)  

كَانَ رَسُولُ اللهِ ﷺ «يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ»  

[Machine] The Messenger of Allah ﷺ used to perform his night prayer by reciting "Subhan Rabbi l-A'la" and "Qul ya ayyuha l-Kafirun" and "Huwa Allah ahad." After completing the prayer, he would say "Subhan al-Malik al-Qudus" three times. Abu 'Abd al-Rahman Shu'bah said: 'Zubayd and Sa'id ibn 'Abd al-Rahman ibn Abza both narrated this hadith to me.'  

كَانَ رَسُولُ اللهِ ﷺ يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ فَإِذَا فَرَغَ مِنَ الصَّلَاةِ قَالَ سُبْحَانَ الْمَلِكِ الْقُدُّوسِ ثَلَاثَ مَرَّاتٍ قَالَ أَبُو عَبْدِ الرَّحْمَنِ شُعْبَةُ أَدْخَلَ بَيْنَ زُبَيْدٍ وَبَيْنَ سَعِيدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ أَبْزَى زِرًّا  

"Shu'bah narrated to us, from Salamah and Zubaid, from Dharr, from Ibn Abdur-Rahman bin Abza from his father that 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 taslim, he would say: Subhanal-Malikil-Quddus (Glory be to the Sovereign, the Most Holy) three times, raising his voice the third time." (Using translation from Nasāʾī 1732)  

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ وَكَانَ يَقُولُ سُبْحَانَ الْمَلِكِ الْقُدُّوسِ ثَلَاثًا وَيَرْفَعُ صَوْتَهُ بِالثَّالِثَةِ