It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) used to recite in bowing (ruku): "O Allah, I have bowed for You, believed in You, and submitted myself to You. You are my Lord. My ears, my eyes, my flesh, and my bones have humbled themselves before You. My feet stand for the Lord, the Sustainer of all the worlds."
Hadith Referenceالسنن المأثورة / باب ما جاء في الأذان / 278
Hadith Takhrijسنن نسائی، التطبيق، باب نوع آخر منه، رقم : 1050 ، وقال الالبانی: صحيح