Sunan Ibn Majah 851
سنن ابن ماجه#851SahihIt was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:“When the reciter says Amin, then say Amin, for the angels say Amin, and if a person’s Amin coincides with the Amin of the angels, his previous sins will be forgiven.”
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari
In-book reference: 5:49