Mishkat al-Masabih #761

Abu Huraira said that God’s Messenger used to observe a period of silence between the takbir and the recitation of the Qur an, so he addressed him thus, “Messenger of God, for whom I would give my father and mother as ransom, what do you say during your period of silence between the takbir and the recitation?” He replied that he said, “O God, remove my sins far from me as Thou hast removed the East far from the West. O God, purify me from sins as a white garment is purified from filth. O God, wash away my sins with water, snow and hail.” (Bukhari and Muslim.)