"Shu'bah narrated to us, he said: Salamah and Zubaid informed me, from Dharr, from Ibn 'Abdur-Rahman bn Abza from Abdur-Rahman, 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 with Subhanal-Malikil-Quddus the third time." (Using translation from Nasāʾī 1733)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ يَقْرَأُ فِي الْوِتْرِ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ ثُمَّ يَقُولُ إِذَا سَلَّمَ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» وَيَرْفَعُ صَوْتَهُ بِالثَّالِثَةِ [272] وَافَقَهُ مَنْصُورٌ فَرَوَاهُ عَنْ سَلَمَةَ عَنْ سَعِيدٍ وَلَمْ يَذْكُرْ ذَرًّا