Why did they say "Anachnu Po bi'Yhudah Yere'im"?
Radak: Even among Bnei Yisrael, we are afraid due to Sha'ul - will we endanger ourselves more among the Pelishtim?!
Malbim: We are here alone, among our Shevet, and still we are afraid - how can we go to Ke'ilah, which is not in Yehudah, to the Pelishti regiments? The war will be from inside (Sha'ul) and outside (Pelishtim)!
Why did David's men not rely on the answer?
Malbim: (a) There is a difference (regarding war) between Makeh Es and Makeh followed by the prefix Beis. The former is striking all of them, like "ha'Makeh Es Midyan" (Bereishis 36:35). The latter means killing some of them; usually the verse tells the number, or says Makah Rabah or a similar expression. David asked "v'Hikeisi ba'Pelishtim", i.e. those who came against Ke'ilah. Hashem said to strike those, and save Ke'ilah. They were concerned lest Pelishtim gather again and strike David's men. (b) The first answer did not promise that the salvation will be miraculous, rather, he will strike them in the way of war. Also, it did not promise that [afterwards] they will dwell safely in Ke'ilah.
