question #1 Sahih Muslim 667, Book 5, Hadith 355 : How does regular prayer contribute to spiritual purification and forgiveness of sins?

He heard the Messenger of Allah (ﷺ) as saying: just see, can anything of his filthiness remain (on the body of) any one of you if there were a river at his door in which he washed himself five times daily? They, said: Nothing of his filthiness will remain (on his body). He said: That is like the five prayers by which Allah obliterates sins.