Chullin 93

Sugya Map

The sugya of chelev she-habasar chofeh oto (fat covered by flesh) on Chullin 93a serves as the anatomical and conceptual clearinghouse for the laws of forbidden fats (chelev). At stake is the physical and semantic boundary of the Torah’s prohibition of chelev, particularly the dialectical tension between fat that is exposed versus fat that is embedded or covered.

• The Core Issue: Does the Torah’s prohibition of chelev apply to all visceral fat, or is it restricted by topological definitions (i.e., only fat that is "upon" the organs, al, rather than "within" or "under" them, be-tokh or tachat)?
• The Nafka Minot (Practical Ramifications):
  • Loben ha-Koliya (The white fat of the kidney): Does the fat embedded within the kidney's tissue require scraping (memarteit) to avoid the capital prohibition of karet, or does it merely require trimming (gayeim) as a rabbinic or customary safeguard?
  • Tat-Chaslei (Fat under the loins): Does the temporary exposure of fat during an animal's locomotion (iporokei miparek) strip it of its "covered" status, retroactively rendering it forbidden de'oraita?
  • Kerumim and Chutin (Membranes and Veins): Are the protective membranes of the spleen and kidneys forbidden inherently as chelev (carrying karet), or are they secondary safeguards (shomer) subject only to rabbinic prohibition?
• Primary Sources:
  • Leviticus 3:3-4 (The foundational verses defining eimurim).
  • Chullin 93a (The Talmudic sugya analyzing Shmuel's rule).
  • Chullin 49b (The cross-reference to the fat on the small intestine).

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Text Snapshot

חלב שהבשר חופה אותו מותר. אלמא, שעל הכסלים אמר רחמנא ולא שבתוך הכסלים. הכא נמי, שעל הכליות אמר רחמנא ולא שבתוך הכליות.

— Chullin 93a:1

Lexical and Grammatical Nuances

The term חופה (chofeh) derives from the root ch-f-h, meaning to cover, drape, or form a canopy (cf. chuppah). The Gemara does not use the passive nikhseh (hidden) or bale'ah (absorbed), but the active-transitive chofeh (canopied/covered). This linguistic choice indicates that the flesh acts as a distinct, protective envelope over the fat.

The transition from the preposition עַל (al - upon/over) in the biblical text to the rabbinic spatial category of שֶׁבְּתוֹךְ (she-be-tokh - that which is inside) establishes a topological rule of construction: only fat whose natural state is superficial and exposed to the abdominal cavity is designated as chelev. Fat that is physically integrated into or covered by skeletal muscle (basar) is classified as shuman (permitted dietary fat).

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Readings

Reading 1: Rashi’s Anatomical Pragmatism and the Ashkenazic Custom

Rashi’s commentary on this sugya is highly detailed and relies on precise anatomical observation:

חלב שהבשר חופה אותו - חלב שעל הכסלים שתחת הכליות ונראה בגובה הכסלים ואח"כ נבלע תחת הבשר אדום דק ומתפשט תחת אותו בשר בכל הכסלים ומשהבשר חופהו מותר...

— Rashi, Chullin 93a:1:1

Rashi localizes this fat as starting near the kidneys, visible at the heights of the flanks (kesalim), and then plunging beneath a thin layer of red skeletal muscle (basar adom dak). He notes a crucial transition: where this red muscle terminates, a thick, white membrane (kerum av ve-lavan) emerges. Underneath this membrane lies more fat.

Rashi records a significant geographic split in practice:

• The Stringent View: Some communities prohibit the fat beneath this thick membrane because they do not consider a mere membrane (kerum) to possess the status of "flesh" (basar) required for chifui (covering).
• The Ashkenazic Leniency: In Ashkenaz, the custom was to permit this fat. Rashi personally validates this, arguing that the membrane, combined with the muscle, constitutes a "complete covering" (chifui gamur).

The Rashash Rashash on Chullin 93a:4 emends Rashi’s text, noting that the phrase "because it is thin" (she-dak hu) should be deleted, as verified by the transcripts of the Rosh and the Tur. The core of Rashi's analysis is that chifui does not require deep, impenetrable skeletal muscle; rather, any stable, physiological layer of tissue that structurally isolates the fat from the abdominal cavity suffices to remove the biblical prohibition of chelev.

Reading 2: The Rif and Rambam on the "White of the Kidney" (Loben ha-Koliya)

The Rif Rif Chullin 30b:1 and the Rambam Mishneh Torah, Forbidden Foods 7:7 rule in accordance with Rav Assi, who permits the fat embedded within the kidney:

ורבינו אלפסי ז"ל והרב רבינו משה בן מיימון ז"ל... פסקו כרב אסי דגאים ליה מדפסק אביי כותיה ומייתי ליה מדשמאל דאמר חלב שהבשר חופה אותו מותר...

— Rashba, Rashba on Chullin 92b:8

The mechanics of this ruling are highly instructive. The Gemara presents a dispute between Rav and Rabbi Chiyya regarding the "white of the kidney" (loben koliya). Rava and Rabbi Yochanan require scraping it (mermeteit/memarteit), which means digging deep into the kidney's tissue to remove the embedded white fat. Rav Assi, however, only requires trimming (gayeim), which means cutting off the exposed surface fat.

Abaye rules that Rav Assi's lenient view is logically compelling because of Shmuel's principle: chelev she-habasar chofeh oto mutar. Since the white fat of the kidney is embedded deep within the organ's tissue, it is considered "covered" and thus biblically permitted. Therefore, no deep scraping is required.

The Rambam codifies this as follows:

חֵלֶב שֶׁהַבָּשָׂר חוֹפֶה אוֹתוֹ, מֻתָּר: לֹא אָסְרָה תּוֹרָה אֶלָּא חֵלֶב שֶׁעַל הַכְּסָלִים, לֹא חֵלֶב שֶׁבְּתוֹךְ הַכְּסָלִים; וְכֵן חֵלֶב שֶׁבְּתוֹךְ הַכְּלָיוֹת, מֻתָּר, וְלֹא אָסְרָה תּוֹרָה אֶלָּא חֵלֶב שֶׁעַל הַכְּלָיוֹת. לְפִיכָךְ, הַלֹּבֶן שֶׁבְּתוֹךְ הַכִּלְיָה--אֵינוֹ חֵלֶב, וּמֻתָּר.

— Mishneh Torah, Forbidden Foods 7:7

The Rambam makes a profound conceptual move here. He does not merely state that the embedded fat is permitted; he declares that it is not chelev (eino chelev). This is a qualitative shift. The covering of the flesh (or the kidney tissue) does not act as a mere exemption (patur) for existing chelev; rather, it fundamentally redefines the substance. Once fat is covered, it loses its ontological status as chelev and is categorized as shuman (permitted fat).

Reading 3: The Rashba's "Middat Chasidut" Reinterpretation

The Rashba Rashba on Chullin 92b:8 faces a severe halakhic challenge: if the halakha follows Rav Assi (who permits the embedded fat and only requires superficial trimming) because of Abaye’s reasoning, why did Rava and Rabbi Yochanan—both of whom are later authorities—practice mermeteit (scraping)? In Talmudic jurisprudence, the halakha typically follows the later authorities (halakha ke-batra'ei), and Rava normally prevails over Abaye.

To resolve this, the Rashba introduces a novel reading of Rava and Rabbi Yochanan's behavior:

והא דרבא ורבי יוחנן דממרטט ליה דילמא מדת חסידות ולהחמיר על עצמו... אבל מדרבא ור' יוחנן לא איסורא שמעינן ולא התירא לעלמא שמעינן.

— Rashba on Chullin 92b:8

The Rashba argues that Rava and Rabbi Yochanan did not actually dispute the core halakha. They agreed that de'oraita, fat covered by flesh or organ tissue is entirely permitted. Their practice of scraping (mermeteit) was a middat chasidut—an act of personal piety and stringency.

By defining their behavior as middat chasidut, the Rashba preserves the authority of Shmuel’s principle as an absolute, uncontested de'oraita truth. This allows him to maintain that the underlying law is entirely lenient, while leaving room for the rigorous purging (nikkur) customs that developed in various Jewish communities.

Reading 4: The Temporal Dimension of "Iporokei Miparek"

The Gemara raises an objection to Shmuel's rule from the status of the fat under the loins (tat-chaslei). This fat is covered by the loin muscle, yet Shmuel himself rules that it is forbidden!

Abaye and Rabbi Yochanan resolve this contradiction by pointing to the animal's movement:

אמר אביי: בהמה בחייה איפרוקי מיפרקא.

— Chullin 93a:2

רבי יוחנן אמר... בהמה בחייה איפרוקי מיפרקא.

— Chullin 93a:3

When the animal is alive and walking, its joints and muscles shift and separate (iporokei miparek), exposing this fat to the abdominal cavity.

This introduces a crucial conceptual principle: Halakhic status is determined by the living state of the animal, not its post-mortem anatomy.

The Minchat Chinuch Minchat Chinuch 147 explores this dynamic. Why do we look at the living state? If the fat is covered at the moment of slaughter (shechitah) and when it is eaten, why should its temporary exposure during life matter?

Two conceptual models emerge to explain this:

1. The Objective Definition Model: The Torah’s definitions of chelev are based on the animal’s active, biological reality. If fat is exposed during the animal's lifetime, it is categorized as "upon the loins" (al ha-kesalim). Once it receives this halakhic designation, it cannot be stripped of it by the post-mortem collapse of the muscles.
2. The Technical Coverage Model: To qualify for the exemption of chelev she-habasar chofeh, the coverage must be permanent and absolute. Temporary coverage that is routinely broken during locomotion does not halakhically qualify as chifui (covering).

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Friction

Kushya: The Kidney Fat Paradox

The Gemara derives the permissibility of covered fat from two parallel biblical exclusions:

1. "Which is upon the loins" (al ha-kesalim) — excluding that which is within the loins (shbe-tokh ha-kesalim).
2. "Which is upon the kidneys" (al ha-kelayot) — excluding that which is within the kidneys (shbe-tokh ha-kelayot).

This dual derivation presents a major conceptual difficulty. If the general rule is that "fat covered by flesh is permitted" (chelev she-habasar chofeh oto mutar), why do we need two separate biblical exclusions?

Furthermore, the physical structure of the kidney is not classical "meat" (basar); it is organ tissue. If organ tissue does not qualify as basar, then the fat inside the kidney should be forbidden, because it lacks chifui basar (flesh covering). Conversely, if organ tissue does qualify as basar, then the fat inside the kidney should be permitted automatically under the general rule of chifui, rendering the specific biblical exclusion of "within the kidneys" redundant!

The Rashba addresses this friction directly:

שאני התם דמדאמר רחמנא ואת שתי הכליות הרי חלב שבתוך הכליות אמור, ואם כן לא איצטריך קרא למיסר אלא שעל הכליות, דמה שבתוך הכליות כבר נאסר כדאמרן...

— Rashba on Chullin 92b:8

Terutz: The Dual Mechanism of Permissibility

To resolve this, we must bifurcate the halakhic mechanisms of permissibility into two distinct categories:

Category	Source of Leniency	Conceptual Mechanism	Physical Application
Chifui Basar (Flesh Covering)	Derived from "upon the loins" (al ha-kesalim)	Structural isolation by skeletal muscle. The fat is physically separated from the abdominal cavity.	Fat under the flank muscles (tat-chaslei), provided it is not exposed during life.
Inherent Non-Chelev (Organ Integration)	Derived from "upon the kidneys" (al ha-kelayot)	Exegetical exclusion of organ-embedded fat. The fat is considered part of the organ itself, not independent chelev.	Loben ha-Koliya (the white fat inside the kidney).

By separating these two mechanisms, we resolve the paradox:

1. The fat inside the kidney is not permitted because of chifui basar (since kidney tissue is indeed not classified as skeletal muscle). Rather, it is permitted because of a specific biblical exclusion: the Torah only prohibited the fat that is "upon" the kidney, leaving the embedded fat as part of the permitted organ tissue.
2. The fat under the loins is permitted because of the structural rule of chifui basar, which applies to skeletal muscle.

This explanation accounts for why the Gemara requires two distinct derivations. They do not merely repeat the same law; they describe two fundamentally different ways that fat can escape the prohibition of chelev.

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Kushya: The Membrane of the Spleen (Kerum ha-Tchol) and the Liability of Karet

The Gemara discusses the conflicting baraitot regarding the membrane of the spleen (kerum ha-tchol):

קרום שעל הטחול אסור ואין חייבין עליו כרת. והתניא חייבין עליו כרת! לא קשיא: הא דעילוי חמרא, הא דלאו דעילוי חמרא.

— Chullin 93a:11

One baraita states that eating the membrane of the spleen carries the capital punishment of karet, while another states it is merely forbidden but does not carry karet. The Gemara resolves this by distinguishing between the membrane on the "thick, fat part" of the spleen (al ha-chamra/ha-shamen) and the membrane on the "thin part."

This distinction is highly problematic. A membrane (kerum) is made of connective tissue, not fat. How can eating a membrane—even one that sits on top of forbidden fat—ever carry the liability of karet? Karet is reserved for eating actual chelev!

Terutz: The "Shomer" vs. "Chada Gfeita" Models of Membrane Prohibition

To resolve how a membrane can carry the liability of karet, the Acharonim propose two distinct models:

Model A: The "Shomer" (Protector/Annex) Model

In this model, the membrane is not considered chelev itself. However, because it is thin and tightly adheres to the underlying fat, it acts as a shomer (protector) for the fat.

In the laws of ritual purity (tumah), a shomer is halakhically annexed to the food it protects. If this principle applies to dietary prohibitions (issurim), the membrane becomes halakhically identical to the underlying fat. Therefore, eating the membrane is considered equivalent to eating the chelev itself, carrying the liability of karet.

Model B: The "Chada Gfeita" (Single Entity) Model

This model, developed in the Brisker school of analysis, argues that the Torah's prohibition of chelev is not limited to pure fat cells. Rather, the Torah prohibits the entire anatomical "fat complex" as a single entity (chada gfeita).

The membrane that covers the thick part of the spleen is structurally integrated into the underlying fat. Halakhically, it is not a "protector" of the fat; it is the outer boundary of the fat itself. On the thin part of the spleen, however, there is no underlying fat; the membrane merely covers the spleen tissue. Therefore, eating the membrane on the thin part is only forbidden as a safeguard (carrying no karet), while eating the membrane on the thick part carries karet because it is an integral part of the forbidden fat complex.

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Intertext

Biblical Source: The Altar-Dietary Interface

The dietary prohibition of chelev is deeply rooted in the sacrificial service (kodashim). The Torah defines the portion of the peace offering (shelamim) that must be burned on the Altar (mizbe'ach):

אֵ֣ת ׀ חֵ֦לֶב הַקֶּ֖רֶב וְאֵת֙ כָּל־הַחֵ֔לֶב אֲשֶׁ֖ר עַל־הַקֶּֽרֶב׃ וְאֵת֙ שְׁתֵּ֣י הַכְּלָיֹ֔ת וְאֶת־הַחֵ֙לֶב֙ אֲשֶׁ֣ר עֲלֵהֶ֔ן אֲשֶׁ֖ר עַל־הַכְּסָלִ֑ים...

— Leviticus 3:3-4

The Torah establishes an absolute conceptual link between the Altar's portion and the human diet:

חֻקַּ֥ת עוֹלָ֛ם לְדֹרֹתֵיכֶ֖ם בְּכֹ֣ל מוֹשְׁבֹתֵיכֶ֑ם כָּל־חֵ֥לֶב וְכָל־דָּ֖ם לֹ֥א תֹאכֵֽלוּ׃

— Leviticus 3:17

This creates a direct structural principle: What is offered to God is withheld from man.

     Sacrificial Altar Portion (Eimurim)
                  │
                  ▼
     Exposed Visceral Fat ("Al")
                  │
                  ▼
     Forbidden for Human Consumption (Chelev)

The permissibility of chelev she-habasar chofeh (covered fat) fits perfectly into this structure. The fat that was covered by flesh or embedded within organs was not burned on the Altar; it remained on the carcass when the eimurim were removed. Because it was never offered to God, it was never prohibited to man. The physical boundaries of the Altar's offering define the halakhic boundaries of the human diet.

Halakhic Codification: Shulchan Arukh Yoreh Deah 64

The Shulchan Arukh codifies the practical details of these laws, outlining the differences between Sephardic and Ashkenazic practice:

חלב שהבשר חופה אותו, מותר. ואם נראה כשמהלך הבהמה, אסור. קרום שעל הטחול, אסור; וצריך לקלפו כולו.

— Shulchan Arukh, Yoreh Deah 64:4-5

The Rama, representing Ashkenazic tradition, adds a significant layer of stringency:

הגה: ויש מקומות שמחמירין עוד בקרומים, ונוהגים לקלוף הטחול... וכל זה מנהג כשר, וכן נוהגין בכל מדינות אלו ואין לשנות.

— Rama, Shulchan Arukh, Yoreh Deah 64:5

The Rama codifies the principle of "Do not forsake the Torah of your mother" (al titosh torat imekha), which the Gemara Chullin 93a:9 applies to Rav Shemen bar Abba regarding crushed testicles.

This highlights a major meta-halakhic transition: From Anatomical Fact to Community Custom.

Even though Shmuel’s sugya permits covered fat and Rav Assi permits the white of the kidney, the historical development of Ashkenazic nikkur (purging) moved toward total restriction. Because the average butcher was no longer deemed expert enough to distinguish between the "thick part" and the "thin part" of membranes, or to identify exactly when a muscle covered the fat, Ashkenazic communities adopted a blanket policy of removing all associated membranes and veins, or avoiding the hindquarters entirely.

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Psak/Practice

The Modern Reality of Nikkur (Porging)

In contemporary halakhic practice, the laws of chelev she-habasar chofeh and the purging of veins and membranes (nikkur) have led to a major divergence between Israel and the Diaspora:

                  ┌────────────────────────┐
                  │ Hindquarters (Achorayim)│
                  └───────────┬────────────┘
                              │
             ┌────────────────┴────────────────┐
             ▼                                 ▼
     [Diaspora Practice]               [Israeli Practice]
   - Nikkur is economically           - Nikkur is widely practiced
     unfeasible due to high             under expert supervision.
     labor costs.                     - Hindquarters are purged
   - Entire hindquarters are            and sold as kosher.
     sold to gentiles.

1. In the Diaspora (Ashkenazic Hegemony): Because nikkur achorayim (purging the hindquarters) is extremely labor-intensive and requires high expertise to identify the sciatic nerve (gid ha-nasheh), the forbidden fats (chelev), and the covered fats (tat-chaslei), it is economically unfeasible. Consequently, Diaspora kosher-certifying agencies do not perform nikkur on the hindquarters; instead, the entire back half of the animal is sold to non-kosher meat purveyors.
2. In Israel (Sephardic and National-Religious Practice): Due to the concentration of expert Sephardic menakkrim (purgers) and different economic conditions, nikkur achorayim is widely practiced under professional rabbinical supervision. The hindquarters are purged of their forbidden fats, veins, and membranes, and sold as kosher.

Meta-Psak Heuristics: The Power of Minhag

This sugya illustrates a powerful meta-psak heuristic: Systemic caution overrides theoretical leniency.

While the lomdus of Chullin 93a demonstrates that covered fat is biblically permitted and does not carry the capital prohibition of karet, the practical halakha has consistently moved toward stringency. The difficulty of anatomical identification, combined with the severity of the prohibition of chelev, led post-Talmudic authorities to treat these areas with extreme caution. What was once a subtle anatomical distinction in the study hall has become a broad customary prohibition, demonstrating how community practice (minhag) shapes the physical boundaries of the kosher kitchen.

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Takeaway

The Torah’s prohibition of chelev is defined by exposure, not just substance; fat covered by flesh is permitted because it was never destined for the Altar. In the development of halakha, the anatomical leniency of "covered fat" has been overtaken by the protective stringency of communal custom, transforming subtle anatomical boundaries into absolute dietary laws.