Sefer Toledot Yeshu or Toledoth Jeschu (ספר תולדות ישו, The Book of the History of Jesus, or Generations of Jesus, or Life of Jesus) is a medieval “anti-gospel” or parody of the Christian gospel. It exists in a number of different versions, none of which are considered either canonical or normative within rabbinic literature, but which appear to have been widely circulated in Europe and the Middle East in the medieval period (though some scholars disagree with this claim).
The stories claim that Jesus was an illegitimate child, and that he practiced magic and heresy, seduced women, and died a shameful death.
But they also show a paradoxical respect for Jesus. As Joseph Dan notes in the Encyclopedia Judaica, "The narrative in all versions treats Jesus as an exceptional person who from his youth demonstrated unusual wit and wisdom, but disrespect toward his elders and the sages of his age."