Musannaf Ibn Abi Shayba 37:382

Ibn Numayr narrated to us, he said: Abu Ya‘fur narrated to us, he said: I heard Abu ‘Amr al-Shaybani saying: I was sitting with Hudhayfah when a Bedouin came until he knelt before him and said: "Has the Dajjal emerged?" Hudhayfah said to him: "And what is the Dajjal? Indeed, what is before the Dajjal is more fearful than the Dajjal. His trial is only forty nights."