John Gills Exposition of the Bible Commentary

Verse 26 (1 Samuel 17:26)

And David spake to the men that stood by him ,.... Who were next to him, looking upon the Philistine, and hearing what he said:

saying, what shall be done to the man that killeth this Philistine ,

and taketh away the reproach from Israel ? which he asked not for the sake of the reward, but to observe the necessity there was of some man's engaging with him, and killing him, or otherwise it would be a reproach to Israel, and to signify that he had an inclination to attempt it:

for who is this uncircumcised Philistine, that he should defy the armies of the living God ? there were two things which provoked David, and raised indignation in him against this man; the one was, the character of the person that reproached, a Philistine, an uncircumcised person, a profane man, that had no true religion in him, an alien from the commonwealth of Israel, and a stranger to the covenants of promise; and the other was the persons whom he reproached, the armies of the living God, of the King of kings, and Lord of lords; and which in effect was reproaching the Lord himself, and which David, filled with zeal for God, and for his people, could not bear; and the consideration of these things animated him to engage with him, not doubting of success.

- John Gills Exposition of the Bible Commentary