It was narrated that Ubayy bin Ka'b said:"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."
أَخْبَرَنَا يَحْيَى بْنُ مُوسَى، قَالَ أَنْبَأَنَا عَبْدُ الْعَزِيزِ بْنُ خَالِدٍ، قَالَ حَدَّثَنَا سَعِيدُ بْنُ أَبِي عَرُوبَةَ، عَنْ قَتَادَةَ، عَنْ عَزْرَةَ، عَنْ سَعِيدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ أَبْزَى، عَنْ أَبِيهِ، عَنْ أُبَىِّ بْنِ كَعْبٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَقْرَأُ فِي الْوَتْرِ بِـ { سَبِّحِ اسْمَ رَبِّكَ الأَعْلَى } وَفِي الرَّكْعَةِ الثَّانِيَةِ بِـ { قُلْ يَا أَيُّهَا الْكَافِرُونَ } وَفِي الثَّالِثَةِ بِـ { قُلْ هُوَ اللَّهُ أَحَدٌ } وَلاَ يُسَلِّمُ إِلاَّ فِي آخِرِهِنَّ وَيَقُولُ يَعْنِي بَعْدَ التَّسْلِيمِ " سُبْحَانَ الْمَلِكِ الْقُدُّوسِ " . ثَلاَثًا .
Nesai
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day • Hadith 1701