1 In the year that king Uzziah died I saw also the Lord sitting upon a throne, high and lifted up, and his train filled the temple.
2 Above it stood the seraphims: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly.
3 And one cried unto another, and said, “Holy, holy, holy, is the LORD of hosts: the whole earth is full of His glory.”
4 And the posts of the door moved at the voice of him that cried, and the house was filled with smoke.
Isaiah has a vision of God’s Throne room.
Uzziah reigned from 727-675BC.
5 Then said I, “Woe is me! For I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the LORD of hosts.
Isaiah realizes his flaws and his unworthiness to be before the throne of God. Knowing sin can’t exist in the presence of God, he fears for his life.
6 Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar:
7 And he laid it upon my mouth, and said, “Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.
God provides cleansing.
8 Also I heard the voice of the Lord, saying, “Whom shall I send, and who will go for us?” Then said I, “Here am I; send me.”
We should always be this eager to do God's work.
9 And He said, “Go, and tell this people, ‘Hear ye indeed, but understand not; and see ye indeed, but perceive not.’
10 “Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed.”
God wants Isaiah to point out to Israel how they are refusing to believe God.
11 Then said I, “Lord, how long?”
“How long will they refuse to understand?”
…And He answered, “Until the cities be wasted without inhabitant, and the houses without man, and the land be utterly desolate,
12 “And the LORD have removed men far away, and there be a great forsaking in the midst of the land.
“Until they are destroyed.”
13 “But yet in it shall be a tenth, and it shall return, and shall be eaten: as a teil-tree, and as an oak, whose substance is in them, when they cast their leaves: so the holy seed shall be the substance thereof.”
“If even a tenth--a remnant--survive, it will be invaded again and burned. But as a terebinth or oak tree leaves a stump when it is cut down, so Israel's stump will be a holy seed." – NLT
God will destroy Israel/Judah, but He will provide for a remnant to be left.
"These verses are quoted in part, or referred to, six times, in the New Testament, which intimates that in gospel time these spiritual judgments would be most frequently inflicted;" -Matthew Henry