Sefer HaYashar (Biblical references)

The Book of Jasher (also, Jashar) or the Book of the Upright or the Book of the Just Man (Hebrew: סֵפֶר הַיׇּשׇׁר‬; transliteration: sēfer hayyāšār) is an unknown book mentioned in the Hebrew Bible. The translation "Book of the Just Man" is the traditional Greek and Latin translation, while the transliterated form "Jasher" is found in the King James Bible, 1611.

The book appears to be referenced from around the reign of David.

David's lament for Jonathan immediately follows. The King James Version of the English Bible has the inclusion "the use of" in italics, material its translator(s) added to render the text into what they considered understandable and comfortable English. Other versions, such as the English Standard Version, David taught his Judaians The Bow, a hypothesised poetic lament of the deaths of Saul and Jonathan. If that interpretation offered in the ESV footnote is accepted, then such a Bow was a lament or a tune contained in the Book of Jashar or which that book also says was taught to the Judaians.

The presence of this event in a book of poetry has been interpreted as a poetic description of the prolonged battle.

According to the Medieval Jewish scholar Rashi, Sefer HaYashar refers to the Pentateuch, as a fulfillment of Jacob's prophecy regarding Ephraim — “His seed will fill the nations” (Gen. 48:19) — and that this prophecy refers to Joshua's renown after the miracle of the standing of the sun.

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