Sahih Al Bukhari Hadith Number 794

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

10  Call to Prayers (Adhaan)
Hadith number 794
Volume no 1
Chapter: 123 (Invocation in bowing.)