'Day of the Lord' in the Bible

The sun will turn to darkness, And the moon to blood, Before the coming of the great, splendid Day of the Lord.

I have handed the man over to Satan, for his physical destruction, in order that his spirit may be saved on the Day of the Lord.

for you yourselves know perfectly well that the Day of the Lord is to come like a thief in the night.

not to let your minds be too easily unsettled or wrought up, by any message of the Spirit or any utterance or letter purporting to be from me, to the effect that the Day of the Lord has already come.

The Day of the Lord will come like a thief; on it the heavens will pass away with a roar, the heavenly bodies will burn up and be destroyed, and the earth and all its works will melt away.