Riyad us Saliheen: Hadith 1045

I heard Messenger of Allah (ﷺ) saying, "When the time for a prescribed Salat is due and a Muslim performs its Wudu' and its acts of bowing and prostration properly, this Salat will be an expiation for his past sins, so long as he does not commit major sins, and this applies for ever."

[Muslim].