"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, elongating his words the third time." (Using translation from Nasāʾī 1734)
عَنْ أَبِيهِ كَانَ رَسُولُ اللهِ ﷺ يُوتِرُ بِسَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى وَقُلْ يَا أَيُّهَا الْكَافِرُونَ وَقُلْ هُوَ اللهُ أَحَدٌ وَكَانَ إِذَا سَلَّمَ وَفَرَغَ قَالَ «سُبْحَانَ الْمَلِكِ» ثَلَاثًا يُطَوِّلُ فِي الثَّالِثَةِ