Sunan an-Nasa'i 61
It was narrated that 'Aishah said:
"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.'"
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا جَرِيرٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم يَقُولُ ‏
"‏ اللَّهُمَّ اغْسِلْ خَطَايَاىَ بِمَاءِ الثَّلْجِ وَالْبَرَدِ وَنَقِّ قَلْبِي مِنَ الْخَطَايَا كَمَا نَقَّيْتَ الثَّوْبَ الأَبْيَضَ مِنَ الدَّنَسِ ‏"‏ ‏.‏