It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "When one of you performs ablution (wudu) and performs it well, then goes out to the mosque with no intention other than the prayer, his left foot keeps erasing a sin and the right foot keeps recording a good deed until he enters the mosque."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13271