(7) بَابُ إِذَا قَالَ أَحَدُكُمْ آمِينَ. وَالْمَلاَئِكَةُ فِي السَّمَاءِ، فَوَافَقَتْ إِحْدَاهُمَا الأُخْرَى، غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "When the Imam, during the prayer, says, "Allah hears him who praises Him', say: 'O Allah! Our Lord! All the praises are for You/, for if the saying of anyone of you coincides with the saying of the angels, his past sins will be forgiven." (JA)
Reference (JA): Sahih al-Bukhari 3228 (JA)
In-book reference (JA): Book 59, Hadith 39 (JA)
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 54, Hadith 451 (JA)