Sayyiduna Abu Hurairah, may Allah be pleased with him, narrated that the Messenger of Allah, peace and blessings be upon him, said: When any one of you says Ameen and the angels in the heavens also say Ameen at the same time, so that one’s Ameen coincides with the other’s Ameen, then all his previous sins are forgiven.
Hadith Referenceاللؤلؤ والمرجان / كتاب الصلاة / 230
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 10 كتاب الأذان: 112 باب فضل التأمين»