Ruku — Bowing
Rukuالرُّكُوع
Bowing with back straight and parallel to the ground — the posture of humility before the Lord of all creation.
سُبْحَانَ رَبِّيَ الْعَظِيمِ
Subhana Rabbiyal 'Azim.
Glory be to my Lord, the Most Great.
Hadith
When you bow, place your palms on your knees and be still. None of you has prayed properly until he does this.
سُبْحَانَ
Subhana
Glory be to
رَبِّيَ
Rabbiya
my Lord
الْعَظِيمِ
al-'Azim
the Most Great