'Day' in the Bible

“But who can endure the day of His coming? And who can stand when He appears? For He is like a refiner’s fire and like fullers’ soap.

“They will be Mine,” says the Lord of hosts, “on the day that I prepare My own possession, and I will spare them as a man spares his own son who serves him.”

“For behold, the day is coming, burning like a furnace; and all the arrogant and every evildoer will be chaff; and the day that is coming will set them ablaze,” says the Lord of hosts, “so that it will leave them neither root nor branch.”

You will tread down the wicked, for they will be ashes under the soles of your feet on the day which I am preparing,” says the Lord of hosts.

“Behold, I am going to send you Elijah the prophet before the coming of the great and terrible day of the Lord.