What is the meaning of "v'Nachnu Alav"?
Rashi: We will camp against him. This is like "va'Yanach 1 b'Chol Gevul Mitzrayim" (Shemos 10:14), "Nachah Aram Al Efrayim" (Yeshayah 7:2).
Why does Rashi learn from the locusts? Did they make an encampment?! (PF)
What is the comparison to dew?
Radak: Just like dew covers the entire land, so we will camp against him.
Malbim: We will confront him during the day, in the light of morning, when dew falls on the ground.
Why does it say "v'Lo Nosar"?
Radak: It means Lo Yivaser; the future is written in past tense. There are many verses like this.
Why will no one remain?
Malbim: Either we will kill everyone 1 , or we will seize the king alive.
Above (15:34), Malbim explained that Chushai would counsel to force David to cede the kingship without fighting! Perhaps now Chushai gave a better counsel how to fight, which also left the possibility of David ceding peaceably, so all would agree with Chushai's counsel. (PF)
