Prophet of Allah (Sallallaahu ‘alaihi wasallam) said:
“When the Imam says:
then you must say, ‘Ameen’, for if one’s utterance of ‘Ameen’ coincides with that of the angels, then his past sins will be forgiven.”
[Sahih Bukhari – Book 60 – Hadith 02]
Please Share this Hadith with your relatives & friends and may Allah SWT reward you.