The Lord will do what is good in his sight

2 Samuel 10:1-19
David sent a delegation to express his sympathy to Hanun concerning his father, but the Ammonite nobles thought David sending men to explore the city and spy it out and overthrow it. So they shamed David's men and hired many foot soldiers from other country ready fight to David.
Be strong and let us fight bravely for our people and the cities of our God. The Lord will do what is good in his sight, Joab said.
David defeated Ammonite/Syrian alliance, so Arameans were afraid to help the Ammonites anymore.
Hanun provoked the war by his outrageous treatment of the ambassadors. But no doubt neighbouring nations were suspicious and afraid of Israel's powerful king.
This victory marks another big extension of the kingdom and David's power over neighbouring nations.
Why?
In background the Lord helped David and let his kingdom more powerful and extension more.
Be strong and let us fight bravely for our people and the cities of our God. They were fight for the God and his people, they has faith to the Lord will do what is good.
How?
The Lord will do what is good in his sight, so I do not afraid, be strong and bravely to do the missions of God.