Ma'mum's Ta'min with or after the Imam's

A: First, the mentioned Hadith is recorded by Al-Bukhari and Muslim in their Two Sahih (authentic) Books of Hadith in the wording: Say, “Amen”, when the Imam says, “Amen”, for if anyone’s utterance of “Amen” coincides with that of the angels, he will be forgiven his past sins. Second, the majority of scholars held the opinion that the Ma’mum (a person being led by an Imam in Prayer) is to say “Amen” with the Imam. They explain the saying of the Prophet (peace be upon him) in the Hadith: Say, “Amen”, when the Imam says, “Amen” with that when the Imam is going to say “Amen”. This is substantiated by what is authentically reported in the Two Sahih on the authority of Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said: When the Imam says, ...not (the way) of those who earned Your Anger (i.e. those who knew the Truth, but did not follow it) nor of those who went astray (i.e. those who did not follow the Truth out of ignorance and error). , say, “Amen” for the Angels say, “Amen” and the Imam says, “Amen”; if anyone’s utterance of “Amen” coincides with that of the angels, he will be forgiven his past sins. (Part No. 5; Page No. 351) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.