Riyad us Saliheen: Hadith 1816

The Messenger of Allah (ﷺ) said, "There has not been a Prophet who has not warned his Ummah of that one-eyed liar (Dajjal). Behold, he is blind in one eye and your Rubb (Allah) is not blind. On his forehead are the letters: (K.F.R.) (meaning Kafir- disbeliever)."

[Al-Bukhari and Muslim].