Albert Barnes Commentary Isaiah 2:12

"For there shall be a day of Jehovah of hosts upon all that is proud and haughty, and upon all that is lifted up; and it shall be brought low;" — Isaiah 2:12 (ASV)

The day ... - This expression evidently denotes that the Lord would inflict severe punishment upon everyone who was lofty. Such a severe infliction is called the day of the Lord of hosts, because it would be a time when he would particularly manifest himself, and when he would be recognized as the inflictor of that punishment. His coming forth in this manner would give character to that time, and would be the prominent event.

The punishment of the wicked is thus frequently called the day of the Lord; (Isaiah 13:6), (Isaiah 13:9): Behold the day of the Lord cometh, cruel both with wrath and fierce anger, etc.; (Jeremiah 46:10): The day of the Lord God of hosts, a day of vengeance. (Ezekiel 30:3); (Zephaniah 1:7), (Zephaniah 1:14); (Joel 2:31); see also in the New Testament, (1 Thessalonians 5:2); (2 Peter 3:10).

Everyone who is proud and lofty - Or, rather, every thing that is high and lofty. The phrase is not restricted to persons, though it embraces them. But though the language here is general, the reference is doubtless, mainly, to the princes, magistrates, and nobility of the nation; and is designed not only to designate them as men of rank and power, but as men who were haughty in their demeanour and feelings. At the same time, there is included in the language, as the subsequent verses show, all on which the nation prided itself.