Again the LORD spoke to Ahaz:
10. And Jehovah added to speak to Ahaz. Moreover, the LORD spake again to Ahaz. — Eng. Ver. As the Lord knew that King Ahaz was so wicked as not to believe the promise, so he enjoins Isaiah to confirm him by adding a sign; for when God sees that his promises do not satisfy us, he makes additions to them suitable to our weakness...
Here, I. God, by the prophet, makes a gracious offer to Ahaz, to confirm the foregoing predictions, and his faith in them, by such sign or miracle as he should choose (Isa 7:10, Isa 7:11): Ask thee a sign of the Lord thy God; See here the divine faithfulness and veracity. God tells us nothing but what he is able and ready to prove.
Commenting on Isaiah 7:10-16
Moreover the Lord spake again unto Ahaz,.... By the prophet Isaiah: saying; as follows: