John Calvin Commentary Isaiah 3:7

"in that day shall he lift up [his voice], saying, I will not be a healer; for in my house is neither bread nor clothing: ye shall not make me ruler of the people." — Isaiah 3:7 (ASV)

In that day he will swear. The word swear expresses an absolute and vehement refusal. Frequently, someone who at first excuses himself, or declares that he will not do it, eventually yields to entreaty. However, one who, in refusing, employs an oath, shuts out all hope, because he indicates to them that his purpose is firm and decided. Perhaps also, the phrase in that day means “immediately, without any delay, and without long consultation.” Yet, since it may also be viewed demonstratively, (δεικτικῶς) as pointing out more fully the time of the calamity, I do not express a strong opinion. The general meaning is obvious: their ruinous condition will be beyond remedy.

Regarding the word חבש, (chobesh) although commentators differ in their interpretation of it, I cheerfully concur with those who think that the metaphor here is borrowed from surgeons, for nothing could be more fitting to the situation. It is as if someone, who had been asked to heal a sick person, were to declare that he has no skill in the art of healing, or that the disease is too deep-seated to be cured.

The next conjunction ו, (vau) means 'for,' as if he had said, “And undoubtedly I do not have the ability to do so.” Therefore, his meaning is that the state of affairs will be so desperate that no one, even when things are at their worst, will venture to take measures for their defense.