1 Samuel 17:47

17:47 and all this assembly will know that it is not by sword or spear that the Lord saves! For the battle is the Lord’s, and he will deliver you into our hand.”

1 Samuel 17:50

17:50 1 David prevailed over the Philistine with just the sling and the stone. He struck down the Philistine and killed him. David did not even have a sword in his hand. 2 

1 tc Most LXX mss lack v. 50.

2 tn Verse 50 is a summary statement; v. 51 gives a more detailed account of how David killed the Philistine.