The Dajjal does not appear in the Qur'an at all. Everything commonly said about him, his one eye, the word "kafir" said to be legible on his forehead, his forty day reign, and the place of his eventual imprisonment before the end times, comes from hadith literature, the collected reports of the Prophet's sayings compiled generations after his death. The hadith collections themselves do not agree on all the details: different narrations describe his appearance, origins, and the specifics of his career with real variation, which is typical of a figure whose portrait grew across generations of oral transmission before being written down and standardized in the major collections.
Scholars of comparative religion have long noted the close structural resemblance between the Dajjal tradition and the Christian Antichrist and certain Jewish apocalyptic false-messiah figures circulating in late antiquity, including shared motifs such as false miracles used to deceive the faithful and a final defeat at the hand of a returning righteous figure, in the Islamic case usually Isa, meaning Jesus. This resemblance is generally read as evidence of shared apocalyptic thought circulating across religious communities in the late antique Near East rather than as one tradition simply borrowing wholesale from another, since each version keeps distinctive features tied to its own theology.