سُبْحَانَ المَلِكِ القُدُّوسِ (ثَلاثَ مَرَّاتٍ، وَ الثَّالِثَةُ يَجْهَرُ بِهَا وَيَمُدُّ صَوْتَهُ يَقُولُ:[ ربِّ المَلائِكَةِ وَالرُّوحِ])

How perfect the King, the Holy One is (Three times, and on the third time the Prophet would raise his voice, elongate it and add: [Lord of the angels and the Rūḥ]).

Reference: How perfect the King, the Holy One is (Three times, and on the third time the Prophet would raise his voice, elongate it and add: [Lord of the angels and the Rūḥ]). Al-Nasāʾī (3/244), al-Dāraquṭnī (2/31) and the extension in brackets is from him and its chain is ṣaḥīḥ. Also see the research of Shuʿayb and ʿAbd al-Qādir Al-Arnāʾūṭ on _Zād al-Maʿād_ (1/337).