This beautiful chapter of Isaiah is a Psalm. Note the sentences of praise:
O Lord I will praise thee.
God is my salvation.
I will trust and not be afraid.
The Lord Jehovah is my strength and my song.
Sing unto the Lord; for he hath done excellent things.
Sounds like David, doesn't it? But believe it or not, it’s Mr. hard-to-read, hard-to-understand Isaiah.