The Messenger of Allah ﷺ used to pause silently between the opening takbir and the recitation. The narrator said, I think he said, briefly.I asked, "May my father and mother be ransomed for you, Messenger of Allah, what do you say during your silence between the takbir and the recitation?"He replied, "I say, 'O Allah, place a great distance between me and my sins, as You have placed a great distance between the east and the west. O Allah, cleanse me of my sins as a white garment is cleansed of filth. O Allah, wash away my sins with water, snow, and hail.'"
كان رسول الله ﷺ يسكت بين التكبير وبين القراءة إسكاتة- قال أحسبه قال: هنية- فقلت: بأبي وأمي يا رسول الله! إسكاتك بين التكبير والقراءة ما تقول؟ قال: أقول: اللهم باعد بيني وبين خطاياي كما باعدت بين المشرق والمغرب، اللهم نقني من الخطايا كما ينقى الثوب الأبيض من الدنس، اللهم اغسل خطاياي بالماء والثلج والبرد.
Bukhari related it in the Book of Adhan (744), and Muslim in the Book of Mosques (598), both through the route of Abdul-Wahid bin Ziyad, who said, "Umara bin Qaqa narrated to us," who said, "Abu Zura narrated to us," who said, "Abu Hurairah narrated to us," and then he related the hadith. The wording given here is Bukhari's.