Invocations during bowing (Ruku)

سُبْحَانَ رَبِّيَ الْعَظِيْمِ

How perfect my Lord is, the Exalted.
(3 Times in Arabic)

[Sunan Abu Dawud – 871]

سُبْحَانَكَ اللّٰهُمَّ رَبَّنَا وَبِحَمْدِكَ اَللّٰهُمَّ اغْفِرْ لِيْ

How perfect You are, O Allah, our Lord, and praise is Yours. O Allah, forgive me.

[Sahih Bukhari – 794]

سُبُّوْحٌ، قُدُّوْسٌ، رَّبُّ الْمَلٰۗئِكَةِ وَالرُّوْحِ

Perfect (are You), Most Holy (are You), Lord of the angels and the Spirit.

[Sahih Muslim – 487]

سُبْحَانَ ذِي الْجَبَرُوْتِ وَالْمَلَكُوْتِ وَالْكِبْرِيَاۗءِ وَالْعَظَمَةِ

How perfect He is, the Possessor of total power, of dominion, of majesty and greatness.

[Sunan Abu Dawud – 873]

اَللّٰهُمَّ لَكَ رَكَعْتُ، وَبِكَ اٰمَنْتُ، وَلَكَ أَسْلَمْتُ خَشَعَ لَكَ سَمْعِيْ، وَبَصَرِيْ وَمُخِّيْ، وَعَظْمِيْ، وَعَصَبِيْ، وَمَا اسْتَقَلَّتْ بِهٖ قَدَمِيْ لِلہِ رَبِّ الْعَالَمِیْنَ

O Allah, unto You I have bowed (in prayer) and in You I have believed and to You I have submitted. Before You my hearing is humbled, as is my sight, my mind, my bones, my tendons and what my feet carry.

[Musnad Ahmad – 1/119]