It wasnarrated that Abu Hurairah said:
The Messenger of Allah (ﷺ)said:"When the reciter says Amin, then say Amin, for if a person'sAmincoincides with the Amin of the angels, his previous sins will beforgiven." (TR)
English reference (TR): Vol. 1, Book 5, Hadith 852 (TR)
Arabic reference (TR): Book 5, Hadith 901 (TR)