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 says, 'Allah hears whoever praises Him,' say 'O Allah! Our Lord, praise be toYou, 'for the previous wrong actions done by the one whose utterance coincides with that of the angels are forgiven."
Muwatta Malik Book 3, Hadith 50
← Previous Hadith Yahya 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."

Muwatta Malik Book 3, Hadith 49 Next Hadith → Yahya related to me from Malik from Muslim ibn Abi Maryam that AIi ibn Abd ar-Rahman al-Muawi said, "Abdullah ibn Umar saw me playing with some small pebbles in the prayer. When I finished he forbade me, saying, 'Do as the Messenger of Allah, may Allah bless him and grant him peace, did.' I said, 'What did the Messenger of Allah, may Allah bless him and grant him peace, do?' He said, 'When he sat in the prayer, he placed his right hand on his right thigh and he closed his fist and pointed his index finger, and he placed his left hand on his left thigh. That is what he used to do.' "

Muwatta Malik Book 3, Hadith 51