Matthew Henry Commentary Isaiah 6:9-13

"And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not. Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they sea with their eyes, and hear with their ears, and understand with their heart, and turn again, and be healed. Then said I, Lord, how long? And he answered, Until cities be waste without inhabitant, and houses without man, and the land become utterly waste, and Jehovah have removed men far away, and the forsaken places be many in the midst of the land. And if there be yet a tenth in it, it also shall in turn be eaten up: as a terebinth, and as an oak, whose stock remaineth, when they are felled; so the holy seed is the stock thereof." — Isaiah 6:9-13 (ASV)

God sends Isaiah to foretell the ruin of His people. Many hear the sound of God's word but do not feel its power. God sometimes, in righteous judgment, gives people up to blindness of mind because they will not receive the truth in the love of it.

But no humble inquirer after Christ needs to fear this awful doom, which is a spiritual judgment on those who will still hold fast to their sins. Let everyone pray for the enlightening of the Holy Spirit, that they may perceive how precious are the Divine mercies, by which alone we are secured against this dreadful danger.

Yet the Lord would preserve a remnant, like the tenth, holy to Him. And blessed be God, He still preserves His church; however, professors or visible churches may be lopped off as unfruitful, the holy seed will shoot forth, from whom all the numerous branches of righteousness shall arise.