Arriving at the battlefield, David approaches the soldiers and enters their conversation by asking about the reward promised to the man who defeats the Philistine champion. His question is surprising, as he has already heard the royal proclamation offering wealth and marriage to the king's daughter.
One approach explains that his inquiry serves simply as a practical way to break the ice, allowing David to speak with the men and ultimately volunteer for the mission [מצודת דוד, ביאור שטיינזלץ]. Beyond a basic conversation starter, his question holds a deeper connection to his own future. Relying entirely on his trust in God, David recognizes that the promised reward, particularly the chance to become the king's son-in-law, will serve as a practical stepping stone toward fulfilling Samuel's prophecy that he will one day rule over the Israelites [רלב״ג].
Conversely, another viewpoint suggests that David is not asking about the reward in order to claim it, but rather to express his profound astonishment at the soldiers themselves. He is shocked that these men require the promise of wealth and property to convince them to fight. In his eyes, the very act of removing the disgrace from the Israelites and avenging the desecration of God's honor is the ultimate reward. A person who is truly zealous for God and His nation should rush into battle driven by a deep sense of mission, rather than a desire for physical compensation [מלבי״ם].
Furthermore, David seeks to reassure the soldiers that achieving victory will be much easier than they imagine. He emphasizes that the moment the enemy dared to insult the honor of God, his fate was sealed. The challenger is already considered a dead man, and God will certainly hand him over to whoever chooses to fight him [אלשיך]. David reinforces this confidence by referring to the enemy dismissively, questioning the actual worth and importance of this impure man. He wonders aloud how such an individual could ever dare to disgrace the armies of God and boldly claim that there is no true hero among the Israelites [מצודת ציון, ביאור שטיינזלץ, מצודת דוד, אלשיך].