It wasnarrated from Abu Hurairah that the Messenger of Allah (ﷺ)said:
"When the reciter says Amin, then say Amin, for the angels sayAmin,and if a person's Amin coincides with the Amin of the angels,hisprevious sins will be forgiven." (PT)
English reference (PT): Vol. 1, Book 5, Hadith 851 (PT)
Arabic reference (PT): Book 5, Hadith 900 (PT)