Why does it specify "Ahalei Yehudah"?
Radak: Besiegers dwell in tents. Also, descendants of Yonadav ben Rechav always dwell in tents (Yirmeyahu 35:6-10). They dwelled amidst Bnei Yehudah.
Radak citing Targum Yonasan: The cities of Yehudah.
Malbim: The first time, Gog will not reach Yerushalayim, only Arei Yehudah. He will want to harm them in their cities and tents. Hashem will save them via a miracle.
Why does it say "ba'Rishonah"?
Rashi: Before Bnei Yerushalayim come to leave the city, they will have a salvation to return to their tents and houses. Afterwards will be the salvation for the city ? "v'Yatza Hashem v'Nilcham" (14:3).
Why does it say "Lema'an Lo Sigdal"?
Rashi: Ben David and Yoshevei Yerushalayim should not boast over [Yehudah], and say 'you were saved only due to us.'
