After giving salaam from the Witr Prayer, Prophet saw would supplicate:

سُبْحَانَ الْمَلِكِ الْقُدُّوْسِ

Glory is to the King, the Holy. [1]

Subhaanal-Malikil-Quddoosi.

...three times,

and then raise and extend the voice on the third time and say:

رَبِّ الْمَلَائِكَةِ وَالرُّوْحِ

Lord of the angels and the Spirit. [2]

Rabbil-malaa'ikati warroohi.