What is the significance of Efrayim seeing his illness?
Malbim: They were not wise to understand that Hashem strikes and destroys them. They thought that it is natural, and needs natural cures to heal it. Therefore, they sent to Melech Ashur to heal it with his army and camp (refer to 5:13:3:3, 5:13:4:1). I.e. Menachem ben Gadi sent 1,000 Kikarim of silver to Melech Ashur (Melachim II, 15:19).
What is "Mezoro"?
Rashi: It is an expression of illness.
Radak: It is a wound. Because Yazuru (they press it), it is called Mazor.
Malbim: Choli is an illness that comes from inside due to ruin of the blend of bodily matters and weakness. Mazor comes from an external wound; they put on it medicinal powder from the outside. Efrayim sent to Ashur to cure an internal rebellion ? this is like an internal illness.
How did Efrayim go to Ashur?
Rashi: This refers to Hoshe'a ben Elah ? he was a slave to Ashur and rebelled.
Radak #1: Efrayim sent messengers.
Radak #2, Malbim: This refers to Menachem ben Gadi, who went to Pul Melech Ashur when Pul came to Eretz Yisrael, and gave to him 1,000 Kikarim of silver to solidify his kingship (Melachim II, 15:19). It helped only for a short time, for Melech Ashur destroyed the land, and also others ravaged it, and Melech Ashur did not help [Efrayim].
Who sent to Melech Yarev?
Rashi: This refers to Achaz, who sent a bribe to Tiglas Pil'eser to help him against Retzin Melech Aram and Pekach ben Remalyahu. Radak ? it must refer to Yehudah, for the previous verse mentions both of them, and here it explains only Efrayim explicitly. Therefore, va'Yishlach must refer to Yehudah. Radak ? Yarev is the name of a city in Ashur. This Sefer mentions it twice. Or perhaps it is another name for Ashur. Malbim ? Yarev hints that Yirev Es Rivo (he should fight his battle) against Pekach and Retzin ? this was from the outside.
Why can he not cure you?
Rashi: There will be many troops of Pelishtim and Araviyim against Achaz, like it says in Divrei ha'Yamim II, 28:21 "Ki Chalak Achaz Es Beis Hashem? va'Yiten El Melech Ashur v'Lo l'Ezrah Lo."
Radak: When Efrayim and Yehudah saw that enemies come against them constantly and plunder them, they sought help from Melech Ashur, and did not turn to Me and ask help from Me, rather, from people. Man cannot help if it is not My desire! Because the affliction was called an illness, it uses an expression of healing.
Malbim: The cure did not help Menachem; Melech Ashur "v'Lo Amad Sham ba'Aretz" (Melachim II, 15:20).
What is the meaning of "v'Lo Yig'heh Mikem Mazor"?
Rashi #1: Pain will not depart from you.
Rashi #2: Yig'heh is a reversed word (the letters are reversed); it is [removal,] like "Ka'asher Hogah Min ha'Mesilah" (Shmuel II, 20:13).
Radak: He will not cure. Similarly, "Lev Same'ach Yetiv Gehah" (Mishlei 17:22) is a cure. He will not cure even one wound of yours. Malbim ? he added to Achaz' afflictions ? "va'Yatzar Lo v'Lo Chazako" (Divrei ha'Yamim II, 28:20).
