And the head of Ephraim is Samaria, and the head of Samaria is Remaliah's son. If ye will not believe, surely ye shall not be established.

Wesley's Notes

7:9 Samaria - Samaria shall continue to be the chief city if the kingdom of Israel, and Pekah shall not conquer Jerusalem. If - If you do not believe this, but seek to the Assyrians for succour, ye shall be consumed thereby.

King James Translators' Notes

If...: or, Do ye not believe? it is because ye are not stable

Jamieson-Fausset-Brown Bible Commentary

9. believe, . be established-There is a paronomasia, or play on the words, in the Hebrew: "if ye will not confide, ye shall not abide." Ahaz brought distress on himself by distrust in the Lord, and trust in Assyria.

Matthew Henry's Concise Commentary

7:1-9 Ungodly men are often punished by others as bad as themselves. Being in great distress and confusion, the Jews gave up all for lost. They had made God their enemy, and knew not how to make him their friend. The prophet must teach them to despise their enemies, in faith and dependence on God. Ahaz, in fear, called them two powerful princes. No, says the prophet, they are but tails of smoking firebrands, burnt out already. The two kingdoms of Syria and Israel were nearly expiring. While God has work for the firebrands of the earth, they consume all before them; but when their work is fulfilled, they will be extinguished in smoke. That which Ahaz thought most formidable, is made the ground of their defeat; because they have taken evil counsel against thee; which is an offence to God. God scorns the scorners, and gives his word that the attempt should not succeed. Man purposes, but God disposes. It was folly for those to be trying to ruin their neighbours, who were themselves near to ruin. Isaiah must urge the Jews to rely on the assurances given them. Faith is absolutely necessary to quiet and compose the mind in trials.