Sunan Abu Dawud
932
Sahih+3

Narrated Wa'il ibn Hujr: When the Messenger of Allah (ﷺ) recited the verse "Nor of those who go astray" (Surah al-Fatihah, verse 7), he would say Amin; and raised his voice (while uttering this word)

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid