'Day of the Lord' in the Bible

Alas for the day. For the day of the LORD is at hand, and it will come as destruction from Shaddai.

Blow the trumpet in Zion, and sound an alarm on my holy mountain. Let all the inhabitants of the land tremble, for the day of the LORD is coming, for it is near.

The LORD thunders his voice before his army; for his forces are very great; for he is strong who obeys his command; for the day of the LORD is great and very awesome, and who can endure it?

The sun will be turned into darkness, and the moon into blood, before the great and terrible day of the LORD comes.

Multitudes, multitudes in the valley of decision. For the day of the LORD is near, in the valley of decision.