The vocative “O house of David” is addressed to Ahaz, using the title appropriate to the southern kingdom’s ruler. The declaration comes as a couplet which Gileadi translates as: “Then Isaiah said, Take heed, O house of David! Is it not enough for you to try the patience of men? Must you also try the patience of my God?” As a king, Ahaz could (and did) impose upon his people, “trying” them perhaps through taxation and conscription; but also he was vexing Yahweh by refusing to accept the sign. Yahweh has offered. Who is Ahaz to refuse?