Maleakhi 3:2-3

3:2 Who can endure the day of his coming? Who can keep standing when he appears? For he will be like a refiner’s fire, ¹  like a launderer’s soap. 3:3 He will act like a refiner and purifier of silver and will cleanse the Levites and refine them like gold and silver. Then they will offer the Lord a proper offering.

[3:2]  ¹ sn The refiner’s fire was used to purify metal and refine it by melting it and allowing the dross, which floated to the top, to be scooped off.