Narrated `Aisha:The Prophet (ﷺ) used to say frequently in his bowing and prostrations "Subhanaka l-lahumma Rabbana wa bihamdika, Allahumma ghfir li" (Exalted [from unbecoming attributes] Are you O Allah our Lord, and by Your praise [do I exalt you]. O Allah! Forgive me). In this way [??] he was acting on what was explained to him in the Holy Qur'an.
حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ سُفْيَانَ، قَالَ حَدَّثَنِي مَنْصُورٌ، عَنْ مُسْلِمٍ، عَنْ مَسْرُوقٍ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّهَا قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم يُكْثِرُ أَنْ يَقُولَ فِي رُكُوعِهِ وَسُجُودِهِ " سُبْحَانَكَ اللَّهُمَّ رَبَّنَا وَبِحَمْدِكَ، اللَّهُمَّ اغْفِرْ لِي " يَتَأَوَّلُ الْقُرْآنَ.
Bukhari
Call to Prayers (Adhaan) • Hadith 212