"The Messenger of Allah ﷺ used to say when bowing and prostrating: 'Subhanakallahumma, Rabbana wa bihamdik. Allahumma-ghfirli (Glory be to You O Allah, Our Lord, and praise. O Allah, forgive me," following the command of the Quran.  

كَانَ رَسُولُ اللَّهِ ﷺ يَقُولُ فِي رُكُوعِهِ وَسُجُودِهِ سُبْحَانَكَ اللَّهُمَّ رَبَّنَا وَبِحَمْدِكَ اللَّهُمَّ اغْفِرْ لِي يَتَأَوَّلُ الْقُرْآنَ