What is the significance of "Matzref la'Kesef v'Chor la'Zahav"?
Rashi: Matzref is the Kli in which they refine Kesef. They make it from oven ashes on earthenware. Chor is the Kli in which they refine gold. It is like a broken pot.
Malbim: To separate dross from silver, a Matzref is needed. Gold is dearer, and its dross clings to it more; Kor is needed. It is a bigger fire.
What is the connection of "Bochen Libos" to the beginning of the verse?
Rashi: Matzref is used to refine silver, and Kor is used to refine gold. Hashem purifies hearts, tests them and knows their intents.
R. Yonah: One who refines removes all the dross. He does not leave impurities with the gold or silver. Hashem tests all Midos of the heart and its intents. Nothing is hidden from His scrutiny. He weighs all the bad against the good, to judge if the heart is good or bad. Man's level is based on the level of his heart in his Midos and thoughts - Hashem desires the heart (Sanhedrin 106b). "Kesef Nim'as Kar'u Lahem Ki Ma'as Hashem Bahem" (Yirmeyah 6:30) - a heart that does not trust in Hashem, rather, in man, is compared to despised silver. It has much dross; the smelter despises it, like the previous verse there says, "la'Shav Tzaraf Tzoref v'Ra'im Lo Nitaku."
Malbim: Hashem tests hearts to purify them from the dross, each based on how it is. Some hearts, the dross does not cling to them so much; they are compared to silver. This is one who sins in known Aveiros due to desire. A small fire refines this. Some make crooked investigations in matters between Emes and Sheker, which are in Binah. This is compared to gold. Investigation and Sechel are more important than deeds. This dross clings more; Kor and a big fire are needed to purify it and test it.
