Book of Jashar (Josh 10:13 conclusion of Joshua’s long day) lit. “book of the upright.” seems to be a book of poetry commemorating the deeds of prominent godly Israelites; now lost.
David saw it coming 1 Sam 26:10; but he still mourns the damage Saul’s sin caused.
II. He Remembered his enemy’s good points
Good points of Saul
v.22 they were mighty warriors
v.23 they were both once lovely
v.24 they brought Israel prosperity
Good of Jonathan - “surpassing the Love of Women” meaning his deep friendship with Jonathan, so here just mourning a friend; but the “love of women” wasn’t that deep in Israel, as women weren’t confidants and equals.