1)
What is "Kor ha'Barzel"?
1.
Rashi: It is earthenware in which gold is refined. Radak - just like gold and silver are refined in a Kor, so Yisrael were refined through the harsh labor in Egypt.
2)
Why did Shlomo mention that Hashem took them from Egypt, from Kor ha'Barzel?
1.
Malbim: Latter exiles are unlike the first exiled in Egypt, They already became Am Hashem. Since He took them out of Kor ha'Barzel once, it is proper that nations not subjugate Yisrael further.
QUESTIONS ON RASHI
3)
Rashi writes that Kor ha'Barzel is earthenware in which gold is refined. It is not made of iron, rather, of earth!
1.
Radak: It says iron to show how strong was the refinement that they were refined there.
