It was narrated that Abu Hurairah said: "The Messenger of Allah (ﷺ) said: “When the reciter says Amin, then say: "Amin" too, for the angels say Amin and if a person's Amin coincides with the Amin of the angels, Allah will forgive his previous sins”"
SahihSahihSahihBook 11 · Hadith 50