Barzel and Barzel, Cutting or Uniting

אמר רבי: האי דמחדדנא מחבראי דחזיתיה לרבי מאיר מאחוריה, ואילו חזיתיה מקמיה הוה מחדדנא טפי — דכתיב: ״והיו עיניך רואות את מוריךךָ״.

The Gemara relates that Rabbi Yehuda HaNasi said: The fact that I am more incisive than my colleagues is due to the fact that I saw Rabbi Meir from behind, i.e., I sat behind him when I was his student. Had I seen him from the front, I would be even more incisive, as it is written: “And your eyes shall see your teacher” (Isaiah 30:20). Seeing the face of one’s teacher increases one’s understanding and sharpens one’s mind.

חָדַד (b. h.) [to cut, point,] to be sharp, pointed.
Pi. - חִידֵּד to sharpen, whet, point. Y. Bets. V, 63ᵇ top לחַדֵּד ראשו וכ׳ they differ as to pointing the top of the spit (on the Holy Day)—Trnsf. to whet the mind, to try somebody’s acumen, to puzzle. Taan. 7ᵃ (ref. to Prov. XXVII, 17) אף … מְחַדְּדִין וכ׳ so do two scholars whet each other’s mind &c. Naz. 59ᵇ, a. e. לא אמר … לחַדֵּד בה וכ׳ R. J. said it only in order to encourage the students in raising points; a. e.—Part. pass. מְחוּדָּד sharpened, well discussed, clear and ready. Kidd. 30ᵃ (ref. to ושננתם, Deut. VI, 7) שיהו ד"ת מְחוּדָּדִים בפיך that the words of the Law be ever ready in thy mouth (Sifré Deut. 34 מְסוּדָּרִים), v. גִּמְגֵּם.
Hithpa. - הִתְחַדֵּד to be whetted. Gen. R. s. 69 אין סכין מִתְחַדֶּדֶת וכ׳ a knife is whetted on the broad side of another, כך אין ת"ח מִתְחַדֵּד וכ׳ so is a student’s mind whetted by a fellow-student, v. supra.

חֲדַד ch. same. Targ. Job XLI, 22. [Targ. Y. I Deut. I, 44 דחַדְדָן which sting; some ed. דחדרן, v. חֲדַר.]
Pa. - חַדֵּד 1) as preced. Pi. Sabb. 32ᵃ (prov.) נפל תורא חַדְּדֵיה לסכינא Ms. M. (ed. חדד, Ms. O. חַדְּדוּ) when the ox is thrown down, sharpen the knife (in critical moments man’s sins are visited, v. חִגְּרָא). Ḥull. 43ᵇ, a. fr. לחַדּוּדֵי וכ׳ to try Abbayis’ acumen.—Part. pass. מְחַדַּד ready in answering questions, well-versed, quick (v. preced.). Erub. 13ᵇ האי דמְחַדַּדְנָא מחבירי Ms. M. (ed. מחבריא) the reason that I am readier than my fellow-students. Yeb. 14ᵃ ב"ש מְחַדְּדֵי טפי those of the school of Sh. were more acute. Nidd. 14ᵇ מחדדי שמעתתיה (read: מְחַדְּדָן), v. infra. —2) to cheer up, entertain. Gitt. 68ᵇ, v. חַדְוְותָא.
Ithpa. - אִיתְחַדַּד to be well studied, ready at hand. Keth. 62ᵇ [read:] מִתְחַדְּדָן שמעתתיה (Rashi: מחדדן) he recited his lessons (traditions) well.
בַּרְזֶ֣ל בְּבַרְזֶ֣ל יָ֑חַד וְ֝אִ֗ישׁ יַ֣חַד פְּנֵֽי־רֵעֵֽהוּ׃
As iron sharpens iron
So a man sharpens the wit of his friend.


JPS adds a comment that what is translated as "wit," panim [in construct form], literally means "face." Some translations pick up on this by saying the friend's "countenance" is sharpened.

יחד פני רעהו. יחד ת"ח מחדדין זה לזה בהלכה:
sharpens the countenance of his friend Heb. יחד, sharpens. Torah scholars sharpen each other in halachah.

"Iron sharpens iron, and a man sharpens the person of his neighbor."

-- Contemporary Aramaic in Plain English trans.

Iron together with iron,

and a man together with his friend. -- Robert Alter (Norton, 2010)

Alter's note:

Iron together with iron. This is usually understood to refer to magnetized iron, which clings to iron, and so does a man to his friend. The force of the proverb is in its terrific compactness, which the translation tries to preserve.


Alter rarely cites his sources, and his claim that his reading is "usual" is belied by the lack of commentary or translation on Sefaria that mentions any reading OTHER than "sharpening." All four English translations on Sefaria use "sharpen" for the verb. The Targum similarly uses "sharpen" -- see below. Of the 38 translations into English on Bible Hub, in addition, only two -- both from the 16th Century -- say anything other than that one "sharpens" either the other individual or the other's face/countenance. Those translations include the old and new JPS. So that makes a to total of 38 of 40 that speak of sharpening, and not one that talks of iron magnetized and sticking to iron. Might be lots of such translation and commentary, but Alter doesn't cite any, so it's hard to understand his reading, however beautiful, as "usual."

Here is one contemporary Christian author, who writes on Ancient Hebrew poetry, reviewing some alternative readings of the verb yud-chet-dalet [יחד] as related to hod, as in "to make joyful," or as related to yachad, "unite, singular," instead of "חדד" to sharpen. Unlike Alter, this teacher cites and discusses sources. (

Here are the two translations using "comfort" instead of "sharpen," just for the record:

"Like as one yro whetteth another, so doth one man comforte another." -- Coverdale Bible, 1535
"Like as one iron whetteth another, so doth one man comfort another." -- Bishops Bible, 1568


פַּרְזְלָא בְּפַרְזְלָא לָטִישׁ וְגַבְרָא לָטִישׁ אַפֵּיהּ דְחַבְרֵיהּ:
לְטֵשׁ, לְטֵישׁ ch. same , to polish, sharpen. Targ. Gen. IV, 22 Levita.—Targ. Prov. XXVII, 17.—Part. pass. לָטִישׁ. Ib.
אָמַר רַבִּי חָמָא בְּרַבִּי חֲנִינָא, מַאי דִּכְתִיב: ״בַּרְזֶל בְּבַרְזֶל יָחַד״, לוֹמַר לָךְ: מָה בַּרְזֶל זֶה — אֶחָד מְחַדֵּד אֶת חֲבֵירוֹ, אַף שְׁנֵי תַּלְמִידֵי חֲכָמִים — מְחַדְּדִין זֶה אֶת זֶה בַּהֲלָכָה.
The Gemara cites other expositions that deal with Torah study. Rabbi Ḥama, son of Rabbi Ḥanina, said: What is the meaning of that which is written: “Iron sharpens iron, so a man sharpens the countenance of his friend” (Proverbs 27:17)? This verse comes to tell you that just as with these iron implements, one sharpens the other when they are rubbed against each other, so too, when Torah scholars study together, they sharpen one another in halakha.

ותחזק מצרים על העם. אחר שלקו בעשר מכות הוצרכו לשלחם בעל כרחם ועוד שנטלו מהם כל ממונם זהו שאמר מיד וינצלו את מצרים, וכן דרשו רז"ל במדרש משלי מאי דכתיב (משלי כ״ז:י״ז) ברזל בברזל יחד ואיש יחד פני רעהו, ברזל בברזל יחד זה משה הצדיק ופרעה הרשע שהיו מתנקשים זה עם זה בדברים ...

כך עשה הקב"ה למצרים לקו ושלחו את ישראל ונטלו את ממונם מי גרם להם על שנתקשו לפני הקב"ה אף הוא נתקשה להם על ידי משה שנאמר ברזל בברזל יחד.

... When Solomon speaks (Proverbs 27,17) about “as iron sharpens iron, so a man sharpens the wit of his friend,” the words “iron sharpens iron” refer to Moses the righteous and Pharaoh the wicked respectively. They were opposing each other with words....

[very long story of opposition]

Pharaoh’s obstinacy was countered by Moses’ obstinacy. This is what Solomon had in mind when he spoke of iron sharpening iron.

כַּ֭מַּיִם הַפָּנִ֣ים לַפָּנִ֑ים כֵּ֤ן לֵֽב־הָ֝אָדָ֗ם לָאָדָֽם׃
As face answers to face in water,
So does one man’s heart to another.

This verse can also relate to Eruvin 13b above.

רַבִּי חָמָא בַּר חֲנִינָא פָּתַח (משלי כז, יז): בַּרְזֶל בְּבַרְזֶל יָחַד, אָמַר רַבִּי חָמָא בַּר חֲנִינָא אֵין סַכִּין מִתְחַדֶּדֶת אֶלָּא בְּיָרֵךְ שֶׁל חֲבֶרְתָּהּ, כָּךְ אֵין תַּלְמִיד חָכָם מִתְחַדֵּד אֶלָּא בַּחֲבֵרוֹ, בַּרְזֶל בְּבַרְזֶל יָחַד וְאִישׁ יַחַד פְּנֵי רֵעֵהוּ, אִישׁ זֶה יַעֲקֹב, כֵּיוָן שֶׁעָמַד אָבִינוּ יַעֲקֹב אִישׁ יַחַד פְּנֵי רֵעֵהוּ, שֶׁנִּתְיַחֲדָה עָלָיו הַשְּׁכִינָה, וְהִנֵּה ה' נִצָּב עָלָיו.
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).