Sayyiduna Uthman bin Affan (may Allah be pleased with him) says: I heard the Messenger of Allah (peace and blessings be upon him) saying: "Whoever performs ablution completely for prayer, then walks to the obligatory prayer and prays it with the people, or with the congregation, or in the mosque, his sins will be forgiven."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 385