Musannaf Ibn Abi Shayba 3:5603

Ibn ‘Uyaynah narrated to us, he said: Perhaps it is from Ibn Jurayj, from ‘Ata’, from Ibn al-Zubayr, who said: The mosque used to have a clamor—or he said: a roar—when the Imam would say, "Not of those who have evoked [Your] anger or of those who are astray," by saying, "Amin."