Allah SWT says:
O you who believe! When you rise to (perform) Salat, wash your faces and your fore arms to the elbows, and wipe over your heads and wash your feet to (including) the ankles.
Allah SWT says: And Allah loves those who purify themselves. (Tawbah 9:108)
Abu Hurairah RA narrates:
I heard Rasulullah SAW saying: My Ummah will called on the Day of Resurrection with their limbs and faces shining from traces of Wudu. So whoever amongst you can increase the area of his radiance should do so (i.e. by performing Wudu regularly). (Bukhari)
Note: Meaning that Wudu should be performed throughly with such care that no part of the skin should remain dry. (Mazahir Haque)
Uthman ibne Affan RA narrates that Rasulullah SAW said: Anyone who performs Wudu and excellently (meaning thereby to carefully observe all the etiquettes), his sins will come out from his body, even coming out from under his nails. (Muslim)Note: The opinion of majority of the scholars is that minor sins, are forgiven by Allah through Wudu , Salat and other forms of worship. The major sins, are forgiven by Istigfar (seeking forgiveness) and Taubah (turning towards Allah with repentance). However, Allah by His bountiful Grace, may even forgive the major sins by virtue of above deeds (Nawawi)