John Calvin Commentary Isaiah 30:3

"Therefore shall the strength of Pharaoh be your shame, and the refuge in the shadow of Egypt your confusion." — Isaiah 30:3 (ASV)

But to you shall the strength of Pharaoh be shame. He now shows what will be the end of the wicked, who despise God and his word, and follow those schemes that are most agreeable to their own views. All that they undertake will tend to their ruin. He threatens not only that they will be disappointed in their hope, but also that they are seeking with great toil, destruction and ruin, from which they will gain nothing but sorrow and disgrace.

To all wicked men it must unavoidably happen that, although for a time they appear to gain their object, and though everything succeeds according to their wish, yet in the end all will be ruinous to them. It is the just reward of their rashness when they go beyond the limits of the word; for nothing that has been acquired by wicked and unlawful methods can be of advantage to any person.

By way of concession, he calls it “the strength of Pharaoh,” as if he were saying, “You think that you gain much protection from Pharaoh, but it will yield you reproach and disgrace. The shadow of Egypt, by which you hoped to be covered, will make you blush for shame.” Accordingly, both expressions, “shame” and “disgrace,” have the same meaning; and as חרפה, (chĕrpāh), reproach, is a stronger expression than “shame,” it is afterwards added to bring out the meaning more fully.