Yahya 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)."
Muwatta Malik Book 3, Hadith 47
← Previous Hadith Yahya related to me from Malik from Ibn Shihab from Ibn Ukayma al-Laythi from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, finished a prayer in which he had recited aloud and asked, "Did any of you recite with me just now?" One man said, "Yes, I did, Messenger of Allah." The Messenger of Allah, may Allah bless him and grant him peace, said, "I was saying to myself, 'Why am I distracted from the Qur'an?' " When the people heard the Messenger of Allah, may Allah bless him and grant him peace, say that, they refrained from reciting with the Messenger of Allah, may Allah bless him and grant him peace, when he recited aloud.

Muwatta Malik Book 3, Hadith 46 Next Hadith → Yahya related to me from Malik from Sumayy, the mawla of Abu Bakr, from Abu Salih as Samman, from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "When the imam has said, 'not of those with whom You are angry nor of those who are in error,' say 'Amin', for the previous wrong actions of the one whose utterance coincides with that of the angels, are forgiven him."

Muwatta Malik Book 3, Hadith 48