"The Messenger of Allah ﷺ would say: [1] 'Allahummaghsil khatayaya bi-ma'ith-thalj wal-barad (O Allah, wash away my sins with the water of snow and hail).'" [1] That is at the beginning of Salah as is clear from the remainder of the narration which preceded under No. 60.
كَانَ رَسُولُ اللَّهِ ﷺ يَقُولُ اللَّهُمَّ اغْسِلْنِي مِنْ خَطَايَاىَ بِالثَّلْجِ وَالْمَاءِ وَالْبَرَدِ