What is the evidence from the Prophetic Sunnah for saying "Amen" three times aloud at the end of Surat al-Fatiha in prayer?

There is no evidence in Islamic legal texts (adillah shar'iyyah) to indicate the permissibility of saying "Ameen" three times in congregational prayer. The hadith narrated by Wa'il ibn Hujr concerning this matter is weak and cannot be used as proof for several reasons:

1. Abd al-Jabbar ibn Wa'il did not hear (hadith) directly from his father. 2. Al-A'mash was the only one to narrate the wording "three times" from Abu Ishaq al-Subai'i, while others who narrated the hadith from him did not mention it. 3. Sa'd ibn al-Salt was not sufficiently authenticated. 4. None of Wa'il ibn Hujr's students who narrated the hadith of "Ameen" from him mentioned this wording.

Even if the chain of narration were sound, the meaning of "three times" might be that he saw him saying "Ameen" in three different prayers, not that he repeated "Ameen" three times in a single prayer.

None of the jurists from the four schools of thought (madhahib al-arba'ah) stated that repeating "Ameen" three times is recommended, with the exception of Ibn Hajar al-Haytami, whose view was not agreed upon by the verifiers (muhaqqiqun) among the Shafi'is.