Muwatta Malik 195
موطأ مالك#195SahihYahya related to me from Malik from Abu'z Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "When one of you says 'Amin' and the angels in the sky say 'Amin' so that one coincides with the other, his previous wrong actions are forgiven him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliSahih
In-book reference: 3:28