When the Prophet ﷺ bowed, he said: "Allahumma laka rak'atu wa bika amantu wa laka aslamtu wa alayka tawwakaltu, anta Rabbi, khasha'a sam'i wa basri wa dammi wa lahmi wa 'azmi wa 'asabi Lillahi Rabbil-'Alamin ( O Allah, to You I have bowed, in You I believe, to You I have submitted and in You I put my trust. You are my Lord. My hearing, my sight, my blood, my flesh, my bones and sinews are humbled before Allah, the Lord of the Worlds.)"  

عَنِ النَّبِيِّ ﷺ كَانَ إِذَا رَكَعَ قَالَ اللَّهُمَّ لَكَ رَكَعْتُ وَبِكَ آمَنْتُ وَلَكَ أَسْلَمْتُ وَعَلَيْكَ تَوَكَّلْتُ أَنْتَ رَبِّي خَشَعَ سَمْعِي وَبَصَرِي وَدَمِي وَلَحْمِي وَعَظْمِي وَعَصَبِي لِلَّهِ رَبِّ الْعَالَمِينَ  

When the Messenger of Allah ﷺ stood to offer a voluntary prayer, he would say when he bowed: "Allahumma laka rak'atu wa bika amantu wa laka aslamtu wa alayka tawwakaltu, anta Rabbi, khasha'a sam'i wa basri wa lahmi wa dammi wa mukhi wa 'asabi Lillahi Rabbil-'Alamin ( O Allah, to You I have bowed, in You I believe, to You I have submitted and in You I put my trust. You are my Lord. My hearing, my sight, my flesh, my blood, my brain and my sinews are humbled before Allah, the Lord of the Worlds)."  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا قَامَ يُصَلِّي تَطَوُّعًا يَقُولُ إِذَا رَكَعَ اللَّهُمَّ لَكَ رَكَعْتُ وَبِكَ آمَنْتُ وَلَكَ أَسْلَمْتُ وَعَلَيْكَ تَوَكَّلْتُ أَنْتَ رَبِّي خَشَعَ سَمْعِي وَبَصَرِي وَلَحْمِي وَدَمِي وَمُخِّي وَعَصَبِي لِلَّهِ رَبِّ الْعَالَمِينَ