Uthman bin `Affan (Radhiallahu anhu) reported:
I saw the Messenger of Allah (Sallallaahu 'alaihi wasallam) performing Wudu' the way I have just done it and said, "He who performs Wudu' like this, his previous sins will be forgiven and his Salat and walking to the mosque will be considered as supererogatory act of worship.''
[Muslim]
Commentary:
Wudu' is a means of remission of minor sins, provided those sins are not related to the rights of people because they too will not be forgiven without penitence and compensating the aggrieved or the wronged.
To perform Wudu' at home before proceeding to the mosque for Salat is highly meritorious. He who does so, will be purged of minor sins. Then his going to the mosque and performance of Salat there, is a means for gaining further reward.
Riyad-us-Saliheen – Hadeeth No. 1027