Malachi 4:
1. "For behold, the day is coming, burning like an oven, and all the proud, yes, all who do wickedly will be stubble. And the day which is coming shall burn them up," says the Lord of hosts, "that will leave them neither root nor branch.
2. But to you who fear My name the Sun of Righteousness shall arise with healing in His wings; and you shall go out and grow fat like stall-fed calves.
NKJV

When God tells us that "the day" is coming, we automatically think it means the end of the world when He will sit as Judge, and this is true.

Here are some scriptures referring to the day of judgement:
1 Thessalonians 5 :
1. But concerning the times and the seasons, brethren, you have no need that I should write to you.
2. For you yourselves know perfectly that the day of the Lord so comes as a thief in the night.
NKJV

2 Peter 3 : 10. But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be burned up.
11. Therefore, since all these things will be dissolved, what manner of persons ought you to be in holy conduct and godliness,
12. looking for and hastening the coming of the day of God, because of which the heavens will be dissolved being on fire, and the elements will melt with fervent heat?
NKJV

But please ...... don't get all caught up in all the fire-works of the day of judgement. Instead concentrate on the question the Apostle Peter asks:
Therefore, since all these things will be dissolved, what manner of person ought you to be in holy conduct and godliness?

That is where our focus needs to be fixed: on who God is making us in our conduct and godly lifestyle, so we will be prepared for this vital day.

Prayer:
Father, today I want to fix my focus on the person You are making me to be.
I want my life today to be pleasing to You,
in Jesus' name,
Amen.