ויקרא, פרק ז׳, פסוק כ״ג

Following the detailed laws of the peace offerings, a fundamental dietary boundary is established regarding the internal parts of an animal. Because the fat and blood are considered the choicest portions chosen to be offered to God on the altar, they are entirely forbidden for human consumption. This restriction applies even when an animal is prepared for a standard, everyday meal [צרור המור, שפתי כהן]. This specific dietary law is directed exclusively at the Israelites, which includes converts and freed slaves, while exempting gentiles from the restriction [מלבי״ם, שפתי כהן, אדרת אליהו].

The prohibition specifically targets the fat of an ox, a sheep, and a goat. The primary approach among commentators is that these three species were singled out because they are the only animals eligible to be brought as sacrifices. Out of respect for the sacrificial service, their fat remains forbidden even when the animal is not dedicated to the altar. Consequently, the fat of impure animals, wild animals such as deer, and birds is completely permitted to eat, as these creatures are never offered on the altar in the first place [רלב״ג, ביאור יש״ר, בכור שור, חזקוני]. Offering a different, mystical perspective, [שפתי כהן] explains that the fat of wild animals is permitted because human souls do not reincarnate into them, whereas domesticated animals possess a unique spiritual complexity that makes eating their fat spiritually restricted.

The forbidden fat is strictly defined as the fatty layer covered by a peelable membrane, which wraps around the internal organs like a garment [פירושי רד״צ הופמן]. By pinpointing the ox, sheep, and goat, the law establishes that only the type of fat shared by all three species is forbidden. This intentionally excludes the fatty tail of the sheep. Although it is sometimes broadly referred to as fat due to its high quality, it is perfectly permissible to eat because such a tail does not exist on an ox or a goat [תורה תמימה, רש״ר הירש].

The scope of this prohibition is remarkably broad. It includes the fat of any hybrid animal bred from these three species [מלבי״ם, צפנת פענח]. Furthermore, the warning against consumption is absolute, forbidding even a microscopic amount. It also covers the fat of an animal whose classification as wild or domesticated is in doubt. While severe divine punishment is reserved for those who eat a significant portion of fat from a confirmed domesticated animal, the basic prohibition still applies to any amount and to any uncertain species [תורה תמימה, אדרת אליהו, רש״ר הירש].

This broad application also teaches that the fat of an ox condemned to be stoned, or a decapitated calf, remains ritually pure and does not spread impurity like a regular animal carcass, even though deriving any benefit from it is forbidden [תורה תמימה]. Finally, the ban on eating this fat is so absolute that it layers on top of other laws. If a person eats the fat of an animal that died of natural causes, or one that was consecrated as a sacrifice, the violations stack. The individual faces a double penalty for a single act of eating. They are held accountable for both consuming forbidden fat and eating from a carcass or a sacred animal [תורה תמימה, שפתי כהן].