(20) باب ذِكْرِ الدَّجَّالِ وَصِفَتِهِ وَمَا مَعَهُ
Anas b. Malik reported that Allah's Messenger (ﷺ) said:
Dajjal is blind of one eye and there is written between his eyes the word" Kafir". He then spelled the word as k. f. r., which every Muslim would be able to read.
Reference: Sahih Muslim 2933 c
In-book reference: Book 54, Hadith 129
USC-MSA web (English) reference(deprecated numbering scheme): Book 41, Hadith 7009