Midrasz do Przysłów 27:17

R. Chama b. Chanina said: "What is the meaning of the passage (Pr. 27, 17) Iron is sharpened by iron? It means just as iron sharpens another iron, so also when two scholars study together, one sharpens [the intellect of] the other." Rabba b. b. Chana said: "Why are the words of the Torah compared to fire? As it is written (Jer. 23, 29) Is not this my word like the fire? saith the Lord. They are to teach that just as fire cannot burn of itself [without having hold of an object], so the words of the Torah can also not remain with one who is alone." And this is also meant by R. Jose b. Chanina; for R. Jose b. Chanina said: "What is the meaning of the passage (Jer. 50, 36) The sword is against the lying soothsayers and they should become foolish. It means that the sword is against the learned who sit alone and study the Torah in privacy. Moreover, they become foolish; as it is said (No'alu) and they shall become foolish; nay, more, they will commit sins; for it is written here (V'noalu) and they shall become foolish, and it is written there (Num. 12, 11) Wherein we have acted foolishly (No'alnu), and wherein we have sinned; and if you wish I would conclude here from (Is. 19, 13) that The princess of Tzo'an are becoming fools (No'alu)."

(Gen. 44:18, cont.:) FOR YOU ARE LIKE PHARAOH. He said to him: Just as Pharaoh is the greatest here, and you are second to him; so Daddy is the greatest in the land of Canaan, and I am second to him. He said: I swear: If I should draw my sword from its scabbard, I am beginning with you, and I am winding up with Pharaoh. Thus it is stated (in Prov. 27:17): IRON SHARPENS IRON. It is fitting for the both of them to stand facing each other; it is fitting for a king to boast facing a king. Judah is a king, about whom it is written (in I Chron. 5:2): JUDAH PREVAILED AMONG HIS BROTHERS. Joseph is a king, about whom it is written (in Gen. 41:43): HE LET HIM RIDE IN THE CHARIOT OF HIS DEPUTY. Therefore, both of them were goring each other. It is therefore stated (in Gen. 44:18): PRAY (bi),¹⁴Bi can also mean AT ME, and the midrash may have this meaning in mind. MY LORD.

“If the iron is dull, and one did not whet the edge, he must intensify his exertion; the advantage is in preparation with wisdom” (Ecclesiastes 10:10).
“If the iron is dull,” if the teacher’s face is dull toward his student like iron,⁵⁰The teacher is not interested in expending energy to explain the material to his students. “and one did not [whet] the edge [panim],” and the teacher does not show the student a friendly countenance [panim], “whet [kilkal],” there is a deterioration [kilkul] in the actions of the student. “He must intensify his exertion” – what should [the student] do? He should bring ten people who will appease the teacher and, ultimately, he will have much preparation for wisdom.⁵¹He will be in a much better position to attain wisdom.
Another matter: “If the iron is dull,” if the student’s face is dull toward his teacher, as it is stated: “Iron sharpens iron; [so a man sharpens the countenance of his friend]” (Proverbs 27:17),⁵²The teacher could be sharpened by the questions and insights of his student, but this student is dull and not insightful. and [therefore,] the teacher does not show the student a friendly countenance, “kilkal,” there is a deterioration [kilkul] in the actions of the student. “He must intensify his exertion” – [the student] should bring ten people who will appease his teacher. “The advantage [veyitron] is in preparation [hakhsheir] with wisdom” – ultimately, he will relinquish [motir] his anger and will enable [veyakhshir] him [to succeed in] his studies.
Another matter: “If the iron is dull,” if your studies have become dull like iron, “and one did not whet the edge,” [your teacher] cannot come to explain it to you, overcome it with your own ability.⁵³If your teacher is no longer alive and you have unresolved questions, work hard to figure out the answers on your own (Etz Yosef).
One of the students of Rabbi Shimon ben Yoḥai forgot his studies. He went crying to the cemetery. As he was crying profusely, he was shown a dream, and [a voice] said to him: When you cast three pebbles at me I will come. That student went to an interpreter of dreams and recounted the incident to him. [The interpreter of dreams] said to him: ‘Recite your studies three times and it will come to you.’⁵⁴Recite each thing you learn three times and you will remember it (Matnot Kehuna). He did so, and so it was for him.
Rabbi Berekhya said: If the nation whose power is as strong as iron, as it is written: “And the Lord took you and brought you out from the iron crucible, from Egypt” (Deuteronomy 4:20), becomes dull; “and one did not whet the edge” – and the Holy One blessed be He is not forthcoming toward the generation; “kilkal” – there are evil deeds in this generation. What shall they do? “He must intensify his exertion” – let them decree fasts, and the Holy One blessed be He will grant them eternal forgiveness.
Rabbi Ḥama bar Pappa said in the name of Rabbi Yehuda ben Rabbi Simon: If the skies above your heads have become dull like iron,⁵⁵There is no rain. as it is stated: “I will render your skies like iron” (Leviticus 26:19), and the Holy One blessed be He is not forthcoming, there are corrupt [kilkal] actions in the generation. What shall they do? They shall decree a fast, and the Holy One blessed be He will provide relief to His world.

Rabbi Chama Bar Chanina opened with the following verse: Iron sharpens iron (Proverbs 27:17). Rabbi Chama Bar Chanina said: A knife will only become sharpened only at the side of another. So too, a Torah scholar can only become sharpened by a friend. "Iron sharpens iron and a person sharpens the face of his neighbor." This is referring to Jacob. When our father Jacob stood together (play on sharpened) with his friend, the Shekinah attached itself (or sharpened) to him. As it says "Behold Adonai stood upon him" (Genesis 28:13).