Abdullah bin Abi Awfa narrated that the Prophet (ﷺ) would supplicate:
Allahumma tahhirni min adh-dhunub wal-khataya. Allahumma naqqini minha kama yunaqqa ath-thawb al-abyad min ad-danas, Allahumma tahhirni bith-thalji wal-barad wal-ma' al-barid (O Allah, purify me of sin and error, O Allah cleanse me of it as a white garment is cleansed of dirt, O Allah purify me with snow and hail and cold water).