Do not mix meat and dairy

Jews affirm that meat and dairy may not be eaten together. The rule is built by the rabbis on the threefold Torah command not to boil a kid in its mother's milk (Exodus 23:19; Exodus 34:26; Deuteronomy 14:21), which the tradition reads as forbidding the cooking, eating, and benefit of meat-and-milk mixtures. Observant practice extends this to waiting a set interval between eating meat and dairy and to keeping separate utensils, pots, and even sinks for each.

The Mishnah (Chullin 8:1-4) extends the biblical wording, which names only a kid boiled in its mother's milk, to all kosher mammal meat and, by later rabbinic decree, to poultry as well, a fence adopted so that fowl would not be mistaken for meat requiring separation. Karaite Jews, who accept the written Torah alone and reject the Oral Torah on which this extension rests, read the verse literally as forbidding only the cooking of a kid in its own mother's milk, and Karaite households do not keep the wholesale separation of meat and dairy dishes that rabbinic law requires. Ashkenazi custom generally waits six hours between eating meat and dairy; Dutch Jews traditionally wait one hour and many German-descended (Yekke) communities three, a divergence rooted in a talmudic dispute over whether the concern is lingering taste or fat caught between the teeth. Fish, eggs, fruit, vegetables, and grains contain neither and are classed pareve, eaten freely with either.

The separation of meat and milk is a leading example of how Jewish law (halakha) develops a detailed observance from a brief scriptural phrase, the threefold repetition being taken to carry threefold force. It is kept across the observant denominations, with communities differing on the length of the waiting period. Together with the categories of permitted animals and the requirement of proper slaughter, it forms one of the three main pillars of the kosher kitchen and a daily, tangible expression of covenant fidelity.

Maimonides codified the rules in his Mishneh Torah (Hilkhot Maakhalot Asurot, twelfth century), systematising centuries of talmudic argument into the form still followed by Orthodox decisors today. Denominations differ sharply on how binding the system remains: Orthodox Judaism and the Conservative movement's own kashrut standards treat the meat-milk separation as binding halakha, while Reform Judaism, since its nineteenth-century German beginnings, has generally treated dietary law as a matter of individual conscience rather than commanded obligation, though many Reform Jews keep some form of it by choice. The rule is among the most visible markers of observant Jewish life: a kitchen, restaurant, or product needs consistent, verifiable separation, not occasional care, to earn kosher certification, which is why supervising agencies audit equipment and supply chains rather than simply the recipe.