Muwatta Malik 193
موطأ مالك#193SahihYahya related to me from Malik from Ibn Shihab that Sa'id ibn al- Musayyab and Abu Salama ibn Abd ar-Rahman told him from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "When the imam says 'Amin', say 'Amin', for the one whose 'Amin' coincides with the 'Amin' of the angels - his previous wrong actions are forgiven him." Ibn Shihab said, "The Messenger of Allah, may Allah bless him and grant him peace, used to say 'Aameen' (extending it)
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: 3:26