Abu Hurairah said: The prophet ﷺ used to say when prostrating himself: “O Allah. Forgive me all my sins, small and great, first and last. “ the narrator Ibn al-sarh added: “open and secret. ”
Hadith Referenceسنن ابي داود / أبواب تفريع استفتاح الصلاة / 878
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم (483)
878. Commentary: ➊ Supplications of this nature by the Messenger of Allah (sallallahu alayhi wa sallam) were for the purpose of expressing gratitude and servitude, and also served as instruction for the Ummah. ➋ From this supplication and those that follow, it becomes completely clear that the Messenger of Allah (sallallahu alayhi wa sallam) is neither the Knower of the unseen nor the absolute disposer of affairs; rather, he is the perfect servant of Allah and a commanded servant (bound by the command of Allah).
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 878