Sunan An-Nasai, Chapter: The Book of Purification

that they went out for the battle of As-Salasil, but they missed the fighting, so they kept watch, then they went back to Mu'awiyah, and Abu Ayyub and 'Uqbah bin 'Amir were with him. 'Asim said: "O Abu Ayyub, we missed the general mobilization, but we have been told that whoever prayers in the four Masjids will be forgiven his sins." He said: "O son of my brother! I will tell you something easir than that. I heard the Messenger of Allah (saw) say: 'Whoever performs Wudu as commanded and prays as commanded, will be forgiven for his previous actions.' Is it not so, O 'Uqbah?" He said: "Yes." (Hasan)