The book of Jasher is referred to in Joshua and second Samuel. Its Name in Hebrew literally means "the upright" or "book of record". The most important value of this book is the large quantity of additional detail it gives to various accounts in the Old Testament than in our bible. The book covers biblical history from the creation of Adam and Eve until t of the initial Israelite conquest of Canaan in the beginning of the book of Judges. For anyone interested in early Hebrew history this book is fascinating. The main differences with the bible are the extra information about pre-flood times, about Enoch, extensive information regarding Abram (Abraham) and his father Tara, a slightly different Garden of Eden story, as well as several pieces of additional information on various events and periods.
It fills in lots of gaps and builds a much more interesting and comprehensive picture. This book was translated into English in 1840 and contains many certificates as to it being an accurate translation. It has extensive prefaces by the owner, the translator and the publisher which are interesting in themselves. It should not be confused with the very different Book of Jasher (Pseudo-Jasher also sometimes called “the books of Jasher”) printed by Jacob Ilive in 1751, which is clearly not the one mentioned in the bible. My edition was purchased new about 50 years ago and is still in very good condition.