Reported by `Uthman bin `Affan (RA): I heard Messenger of Allah (peace be upon him) 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 -Riyad us Saliheen, Chapter 187, 1046 ]
An act of wudu and salat accepted by Allah washes away so much more than physical dirt.