When Uzziah’s grandkid Ahaz was king, Syria and Israel amassed a bunch of troops on the borders of Judah, and everyone in Judah was super freaked out because it looked like war.
So God told Isaiah to go waylay Ahaz while he was chilling at the upper Pool, just off Washerwoman Lane, and to take his kid with him.
Isaiah cornered the king there and was all, God says to tell you that Syria and Israel will lose and that within 65 years, Israel would be destroyed and all the people sent into exile. What sign from God do you want, to verify this is Its words?
Ahaz was all, Far be it from me to make God proof Itself! I don’t need a sign!
Isaiah was all, You’re stupid. God wants to give you a sign. So here it is. A girl will get pregnant and her son will be named Immanuel, and before the kid is 10 or 12, Israel and Syria will be destroyed by Assyria. Got it? See, Assyria is God’s razor and Egypt is Its clippers, and together the two nations will shave the Jews–Head, beard, and balls.