Isaiah 31 - G. Campbell Morgan's Exposition on the Whole Bible

The prophet again denounces the alliance with Egypt. He declares that the sin of it is a false trust consequent on the chosen people tuning their back on Jehovah. The folly of it is manifest in the fact that all their plotting cannot circumvent Jehovah, who is wise, and will certainly proceed against the workers of iniquity.

He then describes the attitude of Jehovah, first as One in whose power the people are as surely as is the prey in the grasp of the lion, and yet He is determined to protect, to deliver, to preserve Jerusalem. In view of this revelation of the divine attitude the prophet appeals to the people to turn again to Him from whom they had revolted. He anticipates their obedience, and describes how in the day of their return they will cast away their idols. This is their true policy, for when they do this, the Assyrian will fall, not by the sword of man, but by the act of Jehovah.