2 Sam 1:18 “and he ordered “The Bow” to be taught to the children of Yehuḏah. See, it is written in the Book of Yashar”

The “bow” in Hebrew is QESET H7198 – qešeṯ, meaning a bow for archers, but also the bow shape as in the RAINBOW, as used in Gen 9:13, “I do set my bow H7198 in the cloud, and it shall be for a token of a covenant between me and the earth.”

Davids’ best friend Jonathan has died. We read in an earlier chapter 1 Samuel 20:37, “when the lad was come to the place of the arrow which Jonathan had shot, Jonathan cried after the lad, and said, Is not the arrow beyond thee?”, which was a signal and warning for David about Sauls’ plot to kill David. Before that Jonathan even gave his bow to David, 1 Samuel 18:4, “And Jonathan stripped himself of the robe that was upon him, and gave it to David, and his garments, even to his sword, and to his bow, H7198 and to his girdle.” Jonathan was obviously known for his bow, being a great archer. In this song that David sings about the bow of Jonathan.

The great tragedy here for David was that his friend was a great archer, but Saul and Jonathan were killed by the Philistine archers, and Saul’s army was short of archers. Had more Israelites know how to use the bow, according to David, they might have been conquerors, and David never wanted Saul to die. Therefor David want to teach this song, as well as the instruction referenced by David, “as written in the Book of Yashar”, that the Israelites should learn to use the Bow.