The Book of Jubilees sometimes called Lesser Genesis presents the history of the division of the days of the Law, of the events of the years, the year-weeks, and the jubilees of the world as revealed to Moses by angels while he was on Mount Sinai for forty days and forty nights. It is an ancient Jewish religious work of 50 chapters, considered canonical by the Ethiopian Orthodox Church as well as Ethiopian Jews, where it is known as the Book of Division .