Harris edits and translates into English an eighth-century Syriac version of the Gospel of the Twelve Apostles that belongs to a well-defined apocalyptic tradition. The document is important not only for its account of the early belief that the Ascension took place on Sunday and that it coincides with Pentecost, as well as other early traditions with regard to the Day of Pentecost, but also on account of its references to the Muslim invasion.