(34) باب الأَمْرِ بِالتَّأْمِينِ خَلْفَ الإِمَامِ
It was narrated that Abu Hurairah, may Allah be pleased with him, that:
The Messenger of Allah (ﷺ) said: "When the Imam says: Not (the way) of those who earned Your anger, nor of those who went astray, say: 'Amin,' for if a person's Amin coincides with the Amin of the angels, his previous sins will be forgiven.'"
Reference: Sunan an-Nasa'i 929
In-book reference: Book 11, Hadith 54
English translation: Vol. 2, Book 11, Hadith 930