Yeshayahu's words constitute a prophecy of consolation and encouragement. This approach subdivides regarding the event about which Achaz is being comforted:
The Aramean-Israelite Threat
All of Yeshayahu's words relate to the threat posed by the Aramean-Israelite alliance. Yeshayahu tells Achaz that he need not worry since both countries are soon to be destroyed by Assyria.
Single message – One of the advantages of this approach is that it presents Yeshayahu as speaking about only one issue, with one unified message, throughout the chapter. Everything the prophet says relates to the downfall of Aram and Israel.
Anger regarding the sign – According to this approach, despite Yeshayahu's anger at Achaz for refusing a Divine sign, the prophet continues to promise Hashem's aid and encourage the king that he has nothing to fear from his enemies.
"יָבִיא י"י עָלֶיךָ... יָמִים אֲשֶׁר לֹא בָאוּ לְמִיּוֹם סוּר אֶפְרַיִם מֵעַל יְהוּדָה" – These words need not connote that calamity is to befall Yehuda; the terms might also relate to good tidings.2 Yeshayahu is prophesying that with the fall of Israel at the hand of Assyria,3 the state of the nation will revert to what it had been before the split of the kingdom,4 when there was just one monarch who ruled over the entire country.5 This might reflect hopes that Chizkiyahu was to revive the Davidic dynasty of old and be a Messianic type of figure.6
Flies of Egypt and bees of Assyria – According to this approach, the mention of the "זְּבוּב אֲשֶׁר בִּקְצֵה יְאֹרֵי מִצְרָיִם" is not intended to connote that Egypt was to join forces with Assyria; it is simply a metaphor for any vast army. As such, the image of both the flies and the bees refer to the swarms of Assyrian soldiers who were to fall upon Aram and Israel.
"תַעַר הַשְּׂכִירָה" – According to this position, the words "מֶלֶךְ אַשּׁוּר" serve to identify the "תַעַר הַשְּׂכִירָה". Assyria is likened to a "razor" as it is about to raze the lands of Aram and Israel until not a hair is left. This approach might agree with Rashi Yeshayahu 7:15-25About R. Shelomo Yitzchakithat "הַשְּׂכִירָה" refers to an honored or important person (or nation), rather than a hired hand.
"Butter and honey"
In both verses 15 and 22, the eating of "butter and honey" is considered a blessing. Yeshayahu declares that after Aram and Israel are defeated, the cattle of the Judeans will give forth so much milk that butter will be made from the leftovers.7 This positive understanding of the image might be supported by its similarity to the phrase "אֶרֶץ זָבַת חָלָב וּדְבָשׁ", a description which consistently has a positive connotation in Tanakh.
Alternatively, while the image in verse 15 is meant positively, in verse 22 the excessive butter is really a sign of the desolation in Aram and Israel.8 Due to the Assyrian invasion, all agricultural produce will be ruined, so that the refugees from war will have only milk to consume.
"לַשָּׁמִיר וְלַשַּׁיִת יִהְיֶה" – The description of desolation in verses 23-25 relates to the lands of Aram and Israel. After they are subdued by Assyria, the land will be barren and overgrown.
Both the Aramean-Israelite and the Assyrian Threat
Yeshayahu tells Achaz that he has nothing to fear from Aram and Israel, since Assyria is soon to ravage both countries. Though Assyria will invade Yehuda as well, Yehuda will survive and Sancheriv's army will be defeated.
"יָבִיא י"י עָלֶיךָ... אֵת מֶלֶךְ אַשּׁוּר" – These sources understand this verse to mean that Yehuda, too, will be attacked by Assyria. Yeshayahu tells Achaz that though he has nothing to fear from Aram and Israel, he should worry about Assyria. He will be plagued by Tiglat Pilesser, and Chizkiyahu9 will be by attacked by Sancheriv.
תַעַר הַשְּׂכִירָה
Rebuke
Yeshayahu's words constitute a rebuke to Achaz for not trusting in Hashem's promise that He will aid Yehuda. As punishment for seeking human assistance, Achaz is told that Assyria will smite not only Aram and Israel, but Yehuda as well.
Refusal to receive a sign – Achaz's refusal to ask for a sign betrayed his lack of belief in Hashem's aid, clarifying to Yeshayahu that Achaz had no intention of heeding his advice to trust in God and not seek foreign assistance ("הִשָּׁמֵר וְהַשְׁקֵט").
The sign: Emanuel – Shadal claims that due to Achaz' refusal to ask for a sign, Yeshayahu gave him one which did not suffice to calm his fears. Since the birth of Emanuel was not to be immediate, Achaz was left to his worries. This ensured that he continued on the path he had set for himself, bribing Assyria to fight against his enemies (See Melakhim II 16:8-9 and Divrei HaYamim II 28:16)
"יָבִיא י"י עָלֶיךָ... אֵת מֶלֶךְ אַשּׁוּר" – According to these sources, the words "יָבִיא י"י עָלֶיךָ" imply that Assyria will attack Yehuda itself. After telling Achaz about the fall of Aram and Israel, Yeshayahu warns Achaz that the very kingdom which he hoped would help him, will eventually turn on him and devastate his country. These sources differ regarding the specific event to which Yeshayahu refers:
Tiglat Pilesser's invasion – According to Shadal, Yeshayahu is speaking of Tiglat Pilesser himself, who attacked Yehuda as Divrei HaYamim shares, "וַיָּבֹא עָלָיו תִּלְּגַת פִּלְנְאֶסֶר מֶלֶךְ אַשּׁוּר וַיָּצַר לוֹ וְלֹא חֲזָקוֹ". Evidence of the destruction resulting from ths invasion can be found in the words of Chizkiyahu as he describes the
Sancheriv's campaign – R"E of Beaugency, in contrast, assumes that Yeshayahu is referring to Sancheriv's campaign against Yehuda in the time of Chizkiyahu.
Biblical and historical parallels – Elsewhere in Tanakh, as well, there are similar warnings that seeking foreign aid rather than trusting in Hashem will result in catastrophe (especially when one invites a foreigner to attack one's brother):
In Divrei HaYamim II 16, when Asa seeks Aram's help against Basha, he is rebuked by the prophet Chanani, "בְּהִשָּׁעֶנְךָ עַל מֶלֶךְ אֲרָם וְלֹא נִשְׁעַנְתָּ עַל י"י אֱלֹהֶיךָ עַל כֵּן נִמְלַט חֵיל מֶלֶךְ אֲרָם מִיָּדֶךָ".
Chizkiyahu's showing of his treasures to Merodakh Baladan of Bavel has been understood as an attempt to join an alliance against Assyria.10 Yeshayahu reacts in anger, warning Chizkiyahu, "הִנֵּה יָמִים בָּאִים וְנִשָּׂא כׇּל אֲשֶׁר בְּבֵיתֶךָ וַאֲשֶׁר אָצְרוּ אֲבֹתֶיךָ עַד הַיּוֹם הַזֶּה בָּבֶלָה". 11
"תַעַר הַשְּׂכִירָה" – The image of a "תַעַר הַשְּׂכִירָה" refers to Assyria, so called because he had been "hired" by Achaz to attack Aram and Israel.
Flies of Egypt – This approach might suggest that Egypt is mentioned, not because they joined forces with Assyria against Yehuda, but because they were another enemy country which Judean kings relied upon and turned to for assistance when dealing with foreign affairs.12 Yeshayahu tells Achaz that any empire in whom he will trust rather than Hashem will ultimately not only fail him, but turn into a foe.13
Butter and honey – According to Shadal. the same image is used to connote opposite concepts in verses 15 and 22. In verse 15, the promise that Emanuel will eat fat and honey is a sign of the upcoming salvation from Aram and Israel, while in verse 22 it signifies the devastation to be wrought on Yehuda. Since all the agricultural land will be laid barren by the Assyrian forces, all that will be left to eat will be the milk produced by cattle. It is possible that the prophet intentionally used the same image to highlight how Achaz' lack of belief turned a promise of blessing into a curse.
"לַשָּׁמִיר וְלַשַּׁיִת יִהְיֶה" – This description of devastation refers to the aftermath of Assyria's attack on Yehuda. Yehuda will be barren, her fruitful vines laid to waste and her land filled with thorns.14 This description might fit either the end of Achaz' era or the aftermath of Sancheriv's campaign. when speaking of his father's reign, Chizkiyahu says, "וַיְהִי קֶצֶף י"י עַל יְהוּדָה וִירוּשָׁלִָם וַיִּתְּנֵם [לְזַעֲוָה] (לזועה) לְשַׁמָּה וְלִשְׁרֵקָה כַּאֲשֶׁר אַתֶּם רֹאִים בְּעֵינֵיכֶם" (Divrei haYamim II 29:8)