What is the meaning of "u'Mi Mechalkel"?
Rashi: Who can measure?
Radak: Who can bear the day that he will come? On that day, many will be refined.
Malbim: Who can bear even the day that He will come, even before He comes? It will be too fearful to bear.
What is the meaning of "u'Mi ha'Omed"?
Rashi: Who can stand?
Malbim: All the more so one cannot stand when He will be revealed (refer to 3:2:3:2)!
What will refine like fire?
Radak: The day mentioned. It will be like fire, which refines impurities from silver. So the Resha'im will be separated from the good. They will perish, and the Tzadikim will remain - "v'Heiveisi Es ha'Shelishis ba'Esh" (Zecharyah 13:9).
Malbim: Hashem is like a refining fire - He removes all dross like fire refines impurities from metals.
What is the comparison to laundering with soap?
Rashi: It removes a stain. So [Hashem] will eradicate all evil. Boris is something that makes clear and purifies, like "l'Varei Levav" (Tehilim 73:1). Radak - Resha'im are the stain - "Nichtam Avonech Lefanai" (Yirmeyahu 2:22).
Malbim: Just like soap removes even a small stain and totally purifies it, so He will purify Yisrael. Fire will consume the Resha'im, who are like dross. Also the Tzadikim He will launder, to remove every stain from them. They will be left like a clean, white garment.
