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.