Reference : Hisn al-Muslim 119

"سبحان الملك القدوس"
ثلاث مرات والثالثة يجهر بها ويمد بها صوته
"ربِّ الملائكةِ والرّوح"
Subḥāna ‘l-Maliki ‘l-Quddūs.
[Recite three times, and raise and extend the voice on the third time and say...]
Rabbi ‘l-Malā'ikati war-rūh.


Glory is to the King, the Holy.
[Recite three times in Arabic, and raise and extend the voice on the third time and say...]
Lord of the angels and the Spirit.

Reference:
An-Nasa'i 3/244, Ad-Daraqutni and others. The final addition is from 
Ad-Daraqutni's version 2/ 31 and its chain of narration is authentic. See 
the checking of Zadul-Ma'ad by Shu'aib Al-Arna'ut and 'Abdul-Qadir 
Al-Arna'ut 1/337.

Chapter: Immediately after salam of the witr prayer