From the First Reading for Wednesday the Fourth Week of Advent, Malachi 3:1–1, 23–24:
Thus says the Lord GOD:Lo, I am sending my messengerto prepare the way before me;And suddenly there will come to the templethe LORD whom you seek,And the messenger of the covenant whom you desire.Yes, he is coming, says the LORD of hosts.But who will endure the day of his coming?And who can stand when he appears?For he is like the refiner’s fire,or like the fuller’s lye.He will sit refining and purifying silver,and he will purify the sons of Levi,Refining them like gold or like silverthat they may offer due sacrifice to the LORD.Then the sacrifice of Judah and Jerusalemwill please the LORD,as in the days of old, as in years gone by.Lo, I will send youElijah, the prophet,Before the day of the LORD comes,the great and terrible day,To turn the hearts of the fathers to their children,and the hearts of the children to their fathers,Lest I come and strikethe land with doom.