Isaiah 7:12 - Ellicott's Commentary On The Whole Bible

I will not ask... — The king speaks as in the very accents of faith. He will not put Jehovah to any such test. Not, perhaps, without a sneer, he quotes almost the very formula of the Law: “Thou shalt not tempt the Lord thy God” (Exodus 17:2; Deuteronomy 6:16). Was the prophet going to forget his own teaching, and become a tempter to that sin? That which lay beneath this show of humble trust was simply self-will and utter unfaith. He had already made up his mind to the Assyrian alliance, against which he knew Isaiah was certain to protest. The fact that the words that follow are spoken to the whole house of David, may, perhaps, imply that the older members of the royal family were encouraging the king in his Assyrian projects, and had, perhaps, suggested his hypocritical answer.