Musnad Ahmad 298:3

Isma'il narrated to us, he said: Ayyub informed us, from Humayd ibn Hilal, from some of their elders, he said: Hisham ibn 'Amir said to his neighbors: "You are walking toward men who were neither more present with the Messenger of Allah, peace and blessings of Allah be upon him, nor more retentive of his hadith than I am. And I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Between the creation of Adam and the establishment of the Hour, there is no matter greater than the Dajjal.'"