Musnad Ahmad 30:3319

Yahya ibn Ghaylan narrated to us, Rushdin narrated to us, 'Amr—meaning Ibn al-Harith—narrated to me, from Sa'id ibn Abi Hilal, that Nu'aym al-Mujmir narrated to him that he prayed behind Abu Hurayrah. He recited the Mother of the Qur'an (Al-Fatiha), and when he said, "Not of those who have evoked [Your] anger or of those who are astray," he said, "Amin." Then he said "Allahu Akbar" to lower his head (for prostration). Then he said when he finished, "By the One in Whose hand is my soul, I am the most similar of you in prayer to the Messenger of Allah, may Allah bless him and grant him peace."