The king of Israel sent back this answer: “A warrior putting on his sword for battle should not boast like a warrior who has already won.”
What does 1 Kings 20:11 mean?
John Gill's Exposition of the Bible
Ver. 11 And the king of Israel answered and said
Very mildly and very wisely:
tell him, let not him that girdeth on his harness boast
himself as he that putteth it off;
that is, he that prepares for the battle as he that has got the
victory; the sense is, let no man triumph before the battle is
over and the victory won; the events of war are uncertain; the
battle is not always to the strong.