Charles Ellicott Commentary Isaiah 1:9

"Except Jehovah of hosts had left unto us a very small remnant, we should have been as Sodom, we should have been like unto Gomorrah." — Isaiah 1:9 (ASV)

Except the Lord of hosts...—This name also had been stamped on the prophet’s mind at the time of his call (Isaiah 6:3). The God of the hosts (or armies) of heaven (sun, moon and stars, angels and archangels) and of earth had not been unmindful of the people. The idea of the “remnant” left when the rest of the people perished is closely connected with the leading thought of Isaiah 6:12-13. It had, perhaps, been impressed on the prophet’s mind by the “remnant” of Israel that had escaped from Tiglath-Pileser or Sargon (2 Chronicles 30:6).

We should have been as Sodom...—Here the prophet, continuing perhaps the thought of Isaiah 1:7, speaks of the destruction, in the next verse of the guilt, of the cities of the plain. Both had passed into a proverb. So Ezekiel (Ezekiel 16:46–56) works out the parallelism; so our Lord speaks of the guilt of Sodom as being lighter than that of Capernaum (Matthew 11:23); so the tradition has condensed itself in the Arabic proverb, quoted by Cheyne, “More unjust than a kadi of Sodom.” (Deuteronomy 32:32).