Hazrat Abu Hurairah, Allah be pleased with him, narrates that the Holy Prophet Muhammad, peace and blessings of Allah be upon him, said:

“Do you think that if there was a river by the door of any one of you, and he bathed in it five times each day, there would be any trace of dirt left on him?” They said, “No trace of dirt would be left on him.” He said, “That is the likeness of the five daily prayers. By means of them, Allah erases sins.”

(Sunan an-Nasai, Kitab al-Salah)