John Calvin on Isaiah 37:22

22. The virgin daughter of Zion. There is greater emphasis in this address to the whole Church than if he had said the same tiring to Hezekiah as a private individual; for this circumstance heightens the baseness of treating with scorn the defencelessness of a wretched people, as if the aid of heaven had been of no avail. Thus he censures the blindness of Sennacherib, in disregarding God and haughtily despising an afflicted Church. Cities are frequently called daughters. (Psalm 9:14.) Sometimes also, as we have formerly seen, delicate cities are called virgins. (Isaiah 1:8, and 23:12.) But here he intended to express the weakness of the city of Jerusalem, because she was like an orphan and destitute virgin, who was insulted by this base ruffian and infamous robber; while God, as the father to whom this insult is offered, declares that he knows well what are the schemes of that wicked man, and what is the condition of the whole of Judea.