Who should make this heard?
Rashi: You Bnei Pelishtim and Bnei Mitzrayim ? announce this and tell in your palaces?
Radak: Their kings and barons who dwell in palaces. This is like "va'Yismach Alayich Oyev" (Eichah 2:17). It is the opposite of "Al Tagidu v'Gas" (Shmuel II, 1:20) ? David said so, and they are Hashem's words.
Malbim (9-10): Above (3), it said that two do not go together if they did not coordinate this. They will announce in Ashdod, which is from Pelishtim. They will stand on palaces (a high place) while announcing to make it heard. They will announce also in Egypt. Also Pelishtim and Egyptians will be astounded at their abomination. This is the opposite of the reason Hashem took them out of Egypt, lest they learn the abominations of Egypt, and He destroyed the Emori, lest Yisrael do like the seven [Kena'ani] nations; Pelishtim are among them. Shomron was worse than them! Who gathered these two nations (Egypt and Pelishtim) to come together to Harei Shomron 1 ? Surely Hashem did!
Malbim (11): Do not ask that we do not find that Pelishtim and Egypt came against Shomron. Not all events are record in Melachim and Divrei ha'Yamim, only matters of the Klal. Presumably, since Pelishtim spread in Yehudah in the days of Achaz, when Melech Ashur came against Pekach, afterwards Pelishtim spread in the borders of Yisrael, who were weakened via Melech Ashur, like it says in Yechezkel (16:27). Also Egypt trampled on Arei Yisrael at the time, like I explained in Hoshe'a (7:11).
Why should they gather to Harei Shomron?
Rashi: From there, they will see their evil way in the city.
Radak: Shomron was a mountain ? "va'Yiken Es ha'Har Shomron" (Melachim I, 16:24). It says Harei (plural) - perhaps there are other mountains around it.
Malbim: They will announce to the nations who gather to go to war on Harei Shomron.
What is the significance of seeing great Mehumah [and Ashukim]?
Radak: Know that they are stricken due to theft among them.
Malbim: They will see that they are worthy to be eradicated, for there is great disturbance in matters Bein Adam la'Makom, and oppression in matters Bein Adam l'Chavero.
