Isaiah 7:2

And it was told the house of David, saying, Syria is confederate with Ephraim. And his heart was moved, and the heart of his people, as the trees of the wood are moved with the wind.

And it was told the house of David (Ahaz and his household), saying, Syria is confederate with Ephraim - is encamped upon the territory of Ephraim (Maurer); or better, as Rezin was encamped against Jerusalem, 'is supported by' (Lowth) Ephraim, whose land lay between Syria and Judah. The Septuagint, Chaldaic, Syriac, and Arabic give much the same sense as the English version. Literally, 'rests upon Ephraim' [ naachaah (H5117), from nuwach, akin to chaanah, to confide] The mention of "David" alludes, in sad contrast with the present, to the time when David made Syria subject to him (2 Samuel 8:6).

Ephraim - the ten tribes.

And his heart was moved, and the heart of his people, as the trees of the wood are moved with the wind

- a simultaneous agitation and alarm.