It is narrated from Sayyida Umm al-Husayn (may Allah be pleased with her), she prayed behind the Messenger of Allah (peace and blessings be upon him), and I heard him say: «مالك يوم الدين» Then when he recited «ولا الضالين», he said: "Ameen" so much so that I heard his voice while I was in the women's row.
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصلوٰة / 189
Hadith Takhrij«المعجم الكبير للطبراني : 158/25 . اسناده ضعيف فيه اسماعيل بن مسلم المكي ، ضعيف الحديث . التقريب : 484 . و ابواسحاق مدلس .»
Explanation & Benefits
Hafiz Abdush Shakoor Tirmidhi
Benefits: The aforementioned narration is weak in its chain of transmission; however, the practice of saying "Ameen" aloud (Ameen bil-jahr) is established from authentic ahadith. The follower (muqtadi) should say "Ameen" upon hearing the imam's "Ameen," even if the follower's recitation is ahead or behind. It is stated in Sunan al-Kubra by al-Bayhaqi: The Tabi'i, Ata bin Abi Rabah rahimahullah, says: "I met two hundred companions of the Prophet sallallahu alayhi wa sallam in this mosque, meaning Masjid al-Haram, that when the imam said 'wa la-d-dallin,' they would raise their voices with 'Ameen.'" .... "I found two hundred noble companions radi Allahu anhum in this Masjid al-Haram (the Sacred Mosque, i.e., the House of Allah), that when the imam said 'wa la-d-dallin,' they would say 'Ameen' aloud." (al-Sunan al-Kubra by al-Bayhaqi, Chapter: The Follower Saying Ameen Aloud, 2/59)