David Boasted Not In Himself, But In God

When David's three oldest brothers had joined Saul's army to fight the Philistines, David, the youngest, went back and forth from his home to the battle field. He had to help his father with the sheep in Bethlehem, as well as deliver food to his brothers and report back to this father as to how his brothers were doing.

On the fortieth day of war, David for the first time heard Goliath shout his usual taunt to the army of Israel, so David asked some soldiers who were standing by what would be a man's reward for killing him. When Eliab, David's oldest brother, overheard David talking to the men, he became very angry at his younger brother. Eliab told David he was arrogant and deceitful.

"But when David's oldest brother, Eliab,

heard David talking to the men, he was angry.

'What are you doing around here anyway?' he demanded.

'What about those few sheep

you're supposed to be taking care of?

I know about your pride and deceit.

You just want to see the battle!'"

1 Samuel 17:28 (NLT)

David was proud, but not in himself.  His pride was in God. When David was able to tackle a lion and a bear with only a club, he gave the credit to God. 

"The Lord who rescued me

from the claws of the lion and the bear

will rescue me from this Philistine!"

1 Samuel 17:37 (NLT)

When David challenged Goliath, he proclaimed the Name of the Lord. He stated emphatically to Goliath the Lord will be the One who will conquer Goliath and rescue the Israelites, not him.

"David replied to the Philistine,

'You come to me with sword, spear, and javelin,

but I come to you in the name of the Lord of  Heaven's Armies---

the God of the armies of Israel, whom you have defied.

Today the Lord will conquer you . . . 

. . . And everyone assembled here will know

that the Lord rescues His people,

but not with sword and spear.

This is the Lord's battle,

and He will give you to us!"

 1 Samuel 17:45, 47a, 47 (NLT)

If David had been proud in himself and not acknowledged God as the source of His strength and power, he would have indeed lost the battle.