When the Messenger of Allah ﷺ bowed in prayer, he would say, "O Allah, to You I have bowed, to You I have submitted, and in You I have believed. My hearing, my sight, my bones, my marrow, and my sinews are humbled before You."
أخبرنا عمرو بن علي قال حدثنا عبد الرحمن بن مهدي قال حدثنا عبد العزيز بن أبي سلمة قال حدثنا عمي الماجشون بن أبي سلمة عن عبد الرحمن الأعرج عن عبيد الله بن أبي رافع
أن رسول الله ﷺ كان إذا ركع قال اللهم لك ركعت ولك أسلمت وبك آمنت خشع لك سمعي وبصري وعظامي ومخي وعصبي
Recorded by Muslim, in the Book of the Prayer of the Traveler, Chapter on the Prayer of the Prophet, peace and blessings of Allah be upon him, and his supplication at night, hadith no. 202/771, from the hadith of Abdul-Rahman bin Mahdi through this route. It is also found in Al-Kubra, hadith no. 637.