The following is the results of your search for Jasher.
Jasher: Upright. "The Book of Jasher," rendered in the LXX. "the Book of the
Upright One," by the Vulgate "the Book of Just Ones," was probably a
kind of national sacred song-book, a collection of songs in praise of
the heroes of Israel, a "book of golden deeds," a national anthology.
We have only two specimens from the book,
1. the words of Joshua which he spake to the Lord at the crisis of
the battle of Beth-horon
(Joshua 10:12,13)
2. "the Song of the Bow," that beautiful and touching mournful
elegy which David composed on the occasion of the death of Saul
and Jonathan
(2 Samuel 1:18-27)