Question
Is there archeological documents of this Book that is mentioned by Joshua (Joshua 10:13), and also David (Samuel 2 1:18), but no where else in the Bible?
Answer
There is no archeological evidence of a book from the Biblical period called The Book of Jashar. Some of the Jewish commentators are of the opinion that “The Book of Jasher” actually refers to Genesis. “Jashar” or the Hebrew “Yashar” means straight or righteous and these commentators understand that this is a reference to the Patriarchs who were exceedingly righteous. There have been numerous other questionable identifications of the “The Book of Jashar” including one notorious forgery which gained quite a bit of popularity.
Rabbi A.Y. Rabenstein