Sayyiduna Abu Ayyub (may Allah be pleased with him) says: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever performs ablution (wudu) as he was commanded and prays as he was commanded, the sins of his past deeds are forgiven him." (Then the narrator asked:) O Uqbah bin Amir! Is it so? He said: Yes.
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3979