Abu Huraira reported: The Messenger of Allah (peace be upon him) said: When the reciter (Imam) utters:” Not of those on whom (is Thine) wrath and not the erring ones,” and (the person) behind him utters Amin and his utterance synchronizes with that of the dwellers of heavens, all his previous sins would be pardoned.
Sahih Muslim, Book 4, Hadith 82
