Charles Ellicott Commentary Isaiah 31:1

"Woe to them that go down to Egypt for help, and rely on horses, and trust in chariots because they are many, and in horsemen because they are very strong, but they look not unto the Holy One of Israel, neither seek Jehovah!" — Isaiah 31:1 (ASV)

Woe to them that go down ... —The Egyptian alliance was, of course, the absorbing topic of the time, and Isaiah returns to it yet again. As in Isaiah 30:16, the princes of Judah were attracted by the prospect of strengthening themselves in their weakest point, and reinforcing the cavalry of Judah, which could hardly be mentioned by an Assyrian ambassador without a smile (Isaiah 36:9), with an Egyptian contingent. Isaiah once more condemns this as trusting in an arm of flesh instead of in the Holy One of Israel.