Musannaf Ibn Abi Shayba 3:3318

Zayd ibn al-Hubab narrated to us, he said: Abd al-Rahman ibn Thawban narrated to us, from his father, from Makhul, who said: Abu A’isha narrated to me—and he was a companion of Abu Hurayrah—he said: I witnessed Sa’id ibn al-’As, and he summoned Abu Musa al-Ash’ari and Hudhayfah, and he asked them about the *takbir* (saying "Allahu Akbar") in the two Eids. Abu Musa said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to say the *takbir* in the Eid just as he would say the *takbir* over the funeral prayer." He said: And Hudhayfah confirmed him. Abu Musa said: "And that is how I used to lead the people of Basra in prayer while I was in charge of them." Abu A’isha said: And I was present for that, so I walked with [them]... his statement: "Four [takbirs], like the *takbir* over the funeral prayer."