(20) باب ذِكْرِ الدَّجَّالِ وَصِفَتِهِ وَمَا مَعَهُ
Anas b. Malik reported that Allah's Messenger (ﷺ) 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).
Reference: Sahih Muslim 2933 a
In-book reference: Book 54, Hadith 127
USC-MSA web (English) reference(deprecated numbering scheme): Book 41, Hadith 7007