It was narrated from Ali bin Abi Talib that:
When the Messenger of Allah (ﷺ) bowed, he said: Allahumma laka rak`atu was laka aslamtu wa bika amantu, khasha`a laka sam`i wa basri wa `izami wa mukhi wa `asabi (O Allah, to You I have bowed and to You I have submitted and in You I have believed. My hearing, sight, bones, brain and sinews are humbled before You).