This paper focuses on a hitherto unknown French text, Moses ben Abraham’s Livre. The Livre dates back to 1244 and is partly a chronicle of ancient history (from the dispersal of Noah’s descendants to the reign of Herod the Great), partly a summary of apocalyptic doctrines, and partly a treaty of biblical and contemporary ethnography. It is based on Hebrew sources (notably, for the historical sections, on the Sefer Yosippon). Moses addressed it to William of Auvergne, bishop of Paris. The Livre is an unprecedented testimony of the usage of French in the Jewish-Christian dialogue on biblical history and scriptural exegesis. Firstly, I describe the Livre’s contents and make a first survey of the sources; secondly, I explain why it was composed; thirdly and finally, I formulate an hypothesis about the circumstances of production of its only manuscript (Den Haag, Koninklijke Bibliotheek, 131 A 3).