Abu Zara' bin 'Amr /Harm أبو زرعة بن عمرو/هرم · The Book of Water

"The Prophet (ﷺ) used to say: 'Allahummaghsil khatayaya bi-ma'ith-thalj wal-barad was naqqi qalbi min al-khataya kama naqayta ath-thawb al-abyad min ad-danas (O Allah, wash away my sins with the water of snow and hail, and cleanse my heart of snow and hail, and cleanse my heart of sin as a white garment is cleansed of filth).'"