JASHAR, BOOK OF (sçpher ha-yâshâr, Book of the Righteous One).An ancient book of national songs, which most likely contained both religious and secular songs describing great events in the history of the nation. In the OT there are two quotations from this book(a) Jos_10:12-13; the original form must have been a poetical description of the battle of Gibeon, in which would have been included the old-world account of Jahweh casting down great stones from heaven upon Israels enemies. (b) 2Sa_1:19-27; in this case the quotation is a much longer one, consisting of Davids lamentation over Saul and Jonathan. In each case the Book of Jashar is referred to as well known; one might expect, therefore, that other quotations from it would be found in the OT, and perhaps this is actually the case with, e.g., the Song of Deborah (Jdg_5:1-31) and some other ancient pieces, which originally may have had a reference to their source in the title (e.g. 1Ki_8:12 f.).
W. O. E. Oesterley.
Hastings' Dictionary of the Bible
Edited by James Hastings, D.D. Published in 1909