וַיֹּ֕אמֶר לְלַמֵּ֥ד בְּנֵֽי־יְהוּדָ֖ה קָ֑שֶׁת הִנֵּ֥ה כְתוּבָ֖ה עַל־סֵ֥פֶר הַיָּשָֽׁר׃
and said—To teach the sons of Judah the bow. Behold, it is written in the book of Jashar:
Read kabbalistic (mystical) interpretation of II Samuel 1:18: and classical mystical sources.