Sahih Al Bukhari Hadith Number 817

Narrated `Aisha: The Prophet (peace be upon him) 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.

10  Call to Prayers (Adhaan)
Hadith number 817
Volume no 1
Chapter: 139 (To invoke and glorify Allah in prostration)