John Gill Commentary 1 Samuel 17:25

"And the men of Israel said, Have ye seen this man that is come up? surely to defy Israel is he come up: and it shall be, that the man who killeth him, the king will enrich him with great riches, and will give him his daughter, and make his father`s house free in Israel." — 1 Samuel 17:25 (ASV)

And the men of Israel said
To one another:

have you seen this man that is come up ?
taken notice of him, and observed him?

surely to defy Israel is he come up ;
to challenge them to fight with him, and upbraid them with cowardice that they did not:

and it shall be [that] the man who killeth him ;
this, and what follows, they said to encourage any person to engage with him, though none of them cared to encounter him themselves:

the king will enrich him with great riches ;
give him a large gratuity, make a present of a great sum of money to him:

and will give him his daughter to be his wife ,
in like manner as Caleb promised to give his daughter in marriage to the person that should take Kirjathsepher, (Judges 1:12) ;

and make his father's house free in Israel ;
from all tributes, taxes, levies, impositions, king's service, and duty; or, as the Targum, "make his father's house freemen, nobles;" raise it to the rank of nobility.