Musnad Ahmad 1034:98

Husayn ibn Muhammad narrated to us, Shayban narrated to us, from Mansur, from Rib'i ibn Hirash, from Hudhayfah ibn al-Yaman, that he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "I am more knowledgeable of what is with the Dajjal than he is. Indeed, with him is a fire that burns"—and Husayn said once: "that burns"—"and a river of cold water. So whoever among you reaches him, let him not perish by it; let him close his eyes and fall into that which he sees as fire, for it is a river of cold water."