عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ رَضِيَ اللَّهُ عَنْهُ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ كَانَ إِذَا رَكَعَ قَالَ: ((اللَّهُمَّ لَكَ رَكَعْتُ وَبِكَ آمَنْتُ وَلَكَ أَسْلَمْتُ، أَنْتَ رَبِّي خَشَعَ سَمْعِي وَبَصَرِي وَمُخِّي وَعَظْمِي وَعَصَبِي وَمَا اسْتَقَلَّتْ بِهِ قَدَمِي لِلَّهِ رَبِّ الْعَالَمِينَ))
It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that when the Noble Prophet (peace and blessings be upon him) performed ruku, he would say: "O Allah! For You I have bowed, in You I have believed, and to You I have submitted. You are my Lord. My hearing, my sight, my mind, my bones, my nerves, and whatever my foot has supported itself with—all have humbled themselves for Allah, the Lord of the worlds."