Why is it written Sheloshim, and we pronounce it Sheloshah?
Radak: They were the greatest and strongest of the Shalishim (captains). This is like "v'Shalishim Al Kulo" (Shemos 14:7). We pronounce it Sheloshah, for these were the three Giborim who descended to David. Malbim - they are the three Giborim mentioned below (verse 16).
What is the meaning of "meha'Sheloshim Rosh"?
Rashi citing Targum Yonasan: From the Giborim, the heads of the camps. Radak - he translated Sheloshim as Shalishim.
Why does it say "El Katzir"?
Radak: It was at the time of harvest, as if it says b'Katzir. Also "v'El ha'Aron Titen Es ha'Edus" (Shemos 25:21) is like uva'Aron. Malbim - the Pelishtim came to destroy Yisrael's harvest.
Why does it say here "El Me'aras Adulam", and in Divrei ha'Yamim I, 11:15, it says "Al ha'Tzur El David El Me'aras Adulam"?
Radak: There was a tall, strong rock there. It is the Metzudah - "v'David Az ba'Metzudah" (verse 14, Divrei ha'Yamim I, 11:16). This was when David fled Sha'ul to Me'aras Adulam. About that place it says "Kol Yemei Heyos David ba'Metzudah" (Shmuel I, 22:4).
Malbim: They came to David to help him. This is the war that David fought against Pelishtim at the beginning of his kingship, when he was in the Metzudah and Pelishtim were in Emek Refa'im (Perek 5).
What is "v'Chayas Pelishtim"?
Radak: It is the camp of Pelishtim, like it says in Divrei ha'Yamim I, 11:15 "u'Machaneh Pelishtim Chonah Emek Refa'im." Chayah is an expression of gathering, like "Chayascha Yashvu Vah" (Tehilim 68:11) is like 'Adascha.'
