In Malachi 3:17, the Lord speaks about the day when he will openly express his favour upon those who fear him and serve him faithfully. There God declares that he will save them as a man spares his own son. In Malachi 4:1 the Lord speaks about the day when he will openly pour out his wrath upon the wicked, who will not be spared, but rather, consumed. The day is the same. It is a day of vindication and reward for the righteous, but a day of condemnation and punishment for the wicked (Matthew 25:46; John 5:29; Romans 2:6–8)
1 “For behold, the day is coming, burning like an oven, when all the arrogant and all evildoers will be stubble. The day that is coming shall set them ablaze, says the LORD of hosts, so that it will leave them neither root nor branch.