Sahih Muslim Book 41, Hadith Number 7007.
Chapter : Account of the Dajjal and his features and what would be along with.
Anas b. Malik reported that Allah’s Messenger (may peace be upon him) said: There is never a prophet who has not warned the Ummah of that one-eyed liar; behold he is one-eyed and your Lord is not one-eyed. On his forehead are the letters k.f.r (Kafir).