When the Messenger of Allah ﷺ bowed, he said: "Allahumma laka rakʿatu was laka aslamtu wa bika amantu, khashaʿa laka samʿi wa basri wa ʿizami wa mukhi wa ʿasabi (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)."  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا رَكَعَ قَالَ اللَّهُمَّ لَكَ رَكَعْتُ وَلَكَ أَسْلَمْتُ وَبِكَ آمَنْتُ خَشَعَ لَكَ سَمْعِي وَبَصَرِي وَعِظَامِي وَمُخِّي وَعَصَبِي