The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1410
In the hadith narrated of the authority of Abd Huraira the Messenger of Allah (may peace be upon him) is reported to have said. while in the hadith narrated by Bakr (the words are like this): He heard the Messenger of Allah (may peace be upon him) 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.