Easton's Bible Dictionary (1897)
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 (Josh. 10:12, 13); and (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 Sam. 1:18-27).
Smith's Bible Dictionary (1863)
(upright),Book of (“the book of the upright”), alluded to in two passages only of the Old Testament. (Joshua 10:13) and 2Sam 1:18 It was probably written in verse; and it has been conjectured that it was a collection of ancient records of honored men or noble deeds. It is wholly lost.
Hitchcock's Bible Names (1869)
righteous; upright
Schaff's Bible Dictionary
JA'SHER, BOOK OF (upright). Twice referred to. Josh 10:13; 2 Sam 1:18; probably a collection of national songs, now lost.