سُبْحَانَ رَبِّيَ الْعَظِيمِ
Meaning: Glory be to my Lord, the Magnificent.
Subhan denotes freedom from imperfection; al-Azim affirms divine magnificence. Three repetitions are the minimum stated for the sunnah, not a condition of the validity of bowing. More repetitions are possible while maintaining due consideration for followers.