Say Amin with the angels

Whoever's Amin matches the angels' Amin is forgiven his past sins.

Narrated by Abu Hurairah

When the imam says Amin, say Amin, for whoever's Amin coincides with the Amin of the angels, his past sins will be forgiven.

Sahih al-Bukhari 780, Sahih Muslim 410

What this hadith teaches

After al-Fatihah the whole congregation says Amin together with the imam, joining the angels.

Reference and grade

Grade
Sahih: agreed upon by al-Bukhari and Muslim
Narrator
Abu Hurairah

The hadith in Arabic نص الحديث

إِذَا أَمَّنَ الإِمَامُ فَأَمِّنُوا فَإِنَّهُ مَنْ وَافَقَ تَأْمِينُهُ تَأْمِينَ الْمَلاَئِكَةِ غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ

Arabic text of Sahih al-Bukhari 780, as given on sunnah.com.