The Amalekite was one of those who came “to strip the slain” on “the morrow” after the battle 1 Samuel 31:8, and had the luck to find Saul and possess himself of his crown and bracelet. He probably started off immediately to seek David, and invented the above story, possibly having heard from some Israelite prisoner an account of what really did happen.
Related Commentaries of 2 Samuel 1:10
2 Samuel 1:10
10 So I stood upon him, and slew him, because I was sure that he could not live after that he was fallen: and I took the crown that was upon his head, and the bracelet that was on his arm, and have brought them hither unto my lord.