Authentic Supplication Number 088.

The Messenger of Allah  used to say in his bowing and his prostration: Subboohun quddoosun rabbul-mala'ikati warroohi (104).

Footnotes.
(104) All-Glorious [free from every deficiency] All-Holy [pure from all that does not befit Thee], Lord of the Angels and of Ar-Rooh [Angel Jibreel, or human souls.]

Reporters.
Reported by Muslim, and is #71 in The Authentic of Good Sayings.