Malachi 3: 1 - 4, 23 - 24
1 "Behold, I send my messenger to prepare the way before me, and the Lord whom you seek will suddenly come to his temple; the messenger of the covenant in whom you delight, behold, he is coming, says the LORD of hosts.
2 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;
3 he will sit as a refiner and purifier of silver, and he will purify the sons of Levi and refine them like gold and silver, till they present right offerings to the LORD.
4 Then the offering of Judah and Jerusalem will be pleasing to the LORD as in the days of old and as in former years.

EWTN