will prepare himself for battle

From something referenced earlier.

You will remember today
I want you to remember that you held nothing back
You did not lose heart
You did not stop fighting
You did not quit

From the OT:

Then David said to the Philistine, "You come to me with a sword, a spear, and a javelin, but I come to you in the name of the LORD of hosts, the God of the armies of Israel, whom you have taunted.

This day the LORD will deliver you up into my hands, and I will strike you down and remove your head from you. And I will give the dead bodies of the army of the Philistines this day to the birds of the sky and the wild beasts of the earth, that all the earth may know that there is a God in Israel, and that all this assembly may know that the LORD does not deliver by sword or by spear; for the battle is the LORD'S and He will give you into our hands."

From the NT:

I have fought the good fight, I have finished the course, I have kept the faith; in the future there is laid up for me the crown of righteousness, which the Lord, the righteous Judge, will award to me on that day;