Musannaf Ibn Abi Shayba 34:188

Yahya ibn Adam narrated to us, he said: Ammar ibn Zurayq narrated to us, from al-A’mash, from Zayd ibn Wahb, from Hudhayfah, who said: "Do you see the Day of the House (Yawm al-Dar)? It was a tribulation—meaning the killing of Uthman—for it is the first of the tribulations, and the last of them is the Dajjal."