(33) باب جَهْرِ الإِمَامِ بِآمِينَ
It was narrated that Abu Hurairah said:
"The Messenger of Allah (ﷺ) said: 'When the reciter says Amin, then say: "Amin" too, for the angels say Amin and if a person's Amin coincides with the Amin of the angels, Allah will forgive his previous sins"
Reference: Sunan an-Nasa'i 925
In-book reference: Book 11, Hadith 50
English translation: Vol. 2, Book 11, Hadith 926