Isaiah 7:9

If ye will not believe, surely ye shall not be established. Note the Figure of speech Paronomasia for emphasis and to attract attention to the importance of the sentence. Hebrew. 'im l'o tha'dminu, ki lo the'amenu, which may be Englished thus: "If ye will not trust, ye shall not be trusted". Greek have no belief... find no relief; or, will not understand.... shall not surely stand; or, no confiding... no abiding. Isaiah 7:17 shows that Ahaz did not trust.

ye. But specially referring to Ahaz. See note on "shall call" (Isaiah 7:14).

surely. [know] that.