Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Isa 31:1-5) The sin and folly of seeking help from Egypt.
(Isa 31:6-9) God's care for Jerusalem.
God will oppose the help sought from workers of iniquity. Sinners may be convicted of folly by plain and self-evident truths, which they cannot deny, but will not believe. There is no escaping the judgments of God; and evil pursues sinners. The Lord of hosts will come down to fight for Mount Zion. The Lion of the tribe of Judah will appear for the defence of his church. And as birds hovering over their young ones to protect them, with such compassion and affection will the Lord of hosts defend Jerusalem. He will so defend it, as to secure its safety.
They have been backsliding children, yet children; let them return, and their backslidings shall be healed, though they have sunk deep into misery, and cannot easily recover. Many make an idol of their silver and gold, and by the love of that are drawn from God; but those who turn to God, will be ready to part with it. Then, when they have cast away their idols, shall the Assyrian fall by the sword of an angel, who strikes more strongly than a mighty man, yet more secretly than a mean man. God can make the stoutest heart to tremble. But if we keep up the fire of holy love and devotion in our hearts and houses, we may depend upon God to protect us and them.