THE SIGN OF IMMANUEL. The supposition that there was a considerable interval between Isaiah 7:9 and Isaiah 7:10 (Cheyne) is quite gratuitous. Nothing in the text marks any such interval. God had sent Ahaz one message by his prophet (Isaiah 7:4-9).
It had apparently been received in silence, at any rate without acknowledgment. The faith had seemed to be lacking which should have embraced with gladness the promise given (see the last clause of Isaiah 7:9).
God, however, will give the unhappy monarch another chance. And so he scuds him a second message, the offer of a sign which should make belief in the first message easier to him (Isaiah 7:11). Ahaz proudly rejects this offer (Isaiah 7:12).
Then the sign of "Immanuel" is given—not to Ahaz individually, but to the whole "house of David," and through them to the entire Jewish people. "A virgin shall conceive, and bear a son, whose name shall be called Immanuel; and before this child shall have grown to the age of moral discernment, God's people will have been delivered, and their enemies made a desolation" (Isaiah 7:14-16).
The exact bearing of the "sign" will be best discussed in the comment upon Isaiah 7:14.