Musnad Ahmad 32:1981

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Qatadah, who said: I heard Anas ibn Malik narrating, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no prophet except that he warned his nation about the one-eyed liar (the Dajjal). Behold, he is one-eyed, and your Lord is not one-eyed. Written between his eyes is: K-F-R (disbeliever)."