"The Prophet (ﷺ) used to say: 'Allahumaghsil khatayaya bi-ma'ith-thalj wal-barad was naqqi qalbi min al-khataya kama naqayta ath-thawb al-abyad min ad-danas (O Allah, was away my sins with the water of snow and hail, and cleanse my heart of sin as a white garment is cleansed of filth.'"
Sunan an-Nasa'i Book 1, Hadith 61
← Previous Hadith "When the Messenger of Allah (ﷺ) started Salah, he would remain silent for a short while. I said: 'May my father and mother be ransomed for you, O Messenger of Allah! What do you say when you remain silent between the Takbir and the recitation (in the Salah)?' He said: 'I say: Allahumma ba'id baini was baina khatayaya kama ba'adta baina al-mashriq wal-maghrib; Allahumma naqqini min khatayaya kama yunaqqath-thawb al-abyad min ad-danas; Allahummaghsilni min khatayaya bith-thalji wal-ma'i wal-barad (O Allah, out a great distance between me and my sins, as great as the distance You have made between the East and the West; O Allah, cleanse me of of sin as a white garment is cleansed from filth; Wash away my sins with snow, water, and hail)'."

Sunan an-Nasa'i Book 1, Hadith 60 Next Hadith → "I heard the Messenger of Allah (ﷺ) offering the (funeral) prayer for one who had died, and I heard him say in his supplication: 'Allahummaghfir lahu warhamhu wa 'afihi was a'fu 'anhu, wa akrim nuzulahu wa wassi' ,adkhalahu waghsilhu bil-ma'i wath-thalji wal-baradi wa naqqihi min al-khataya kama ynaqqath-thawb al-abyad min ad-danas. (O Allah, forgive him and have mercy on him, keep him safe and sound and forgive him, honor the place where he settles and make his entrance wide; wash him with water and snow and hail, and cleanse him of sin as a white garment is cleansed of dirt)."

Sunan an-Nasa'i Book 1, Hadith 62