Yahya related to me from Malik from Sumayy, the mawla of AbuBakr, from Abu Salih as Samman, from Abu Hurayra that the Messenger ofAllah, may Allah bless him and grant him peace, said, "When the imamhas said, 'not of those with whom You are angry nor of those who arein error,' say 'Amin', for the previous wrong actions of the one whoseutterance coincides with that of the angels, are forgiven him."
App reference: Book 3, Hadith 48
USC-MSA web (English) reference: Book 3, Hadith 48
Arabic reference: Book 3, Hadith 195