Question: If an akum uses your pot to cook himself (kosher) food, must you kasher the pot?
Short Answer: We pasken that the pot must be kashered.
I. Rashba vs. Rosh
The Rashba (Toras HaBayis, cited in the Beis Yosef, Yoreh Dei’ah 113:16) writes that pots that were used by an akum (even if used for kosher food), require hechsher. The Rashba compares this to other isurim that are only d’Rabbanan, such as the fat of gid ha’nasheh and kechal (udder), that get absorbed into a pot. The pot must be kashered because “k’ein d’Oraisa tikun,” that when the chachamim instituted these Rabbinic prohibitions, they enacted them with the same rules as d’Oraisa prohibitions.
The Beis Yosef also cites the Sefer HaT’rumah, who rules that it is forbidden to eat dough that absorbed bishul akum fish juice even though the juice is only from a Rabbinic prohibition.
On the other hand, the Rosh (cited in the Tur, ibid) rules that pots that were used for bishul akum do not require kashering. The Beis Yosef adds that this is the opinion of the Re’ah as well. The chachamim never instituted this prohibition on pots (or the absorption of bishul akum) because the reasoning of intermarriage does not apply. In other words, there is no fear that a person will come to marry an akum based on his usage of a pot that an akum previously used to cook food.
II. Following the Strict Opinion
The Shulchan Aruch (Yoreh Dei’ah 113:16) cites both opinions, first citing the strict opinion of the Rashba, and then the lenient opinion of the Rosh as a “yeish omrim” (“some say”). The Shach (20) cites the Toras Chayim, who adopts the ruling of the Shulchan Aruch and warns against allowing an akum to cook for him/herself even in a Jewish house. The Shach explains that we are even stricter when an akum cooks for him/herself, because the earlier leniency of the Rama – that a Jew invariably will perform some act of cooking on the food – does not really occur in this situation.
Many Acharonim adopt this ruling, as well, including the Chochmas Adam (66:11), the Aruch HaShulchan (113:50), and the Mishnah B’rurah (Orach Chayim 328:63).
III. The Tzitz Eliezer’s Explanation
What is the explanation of this machlokes between the Rashba and the Rosh? While the Rashba is clear that we apply the principle of “k’ein d’Oraisa tikun” to require the pots to be kashered, what is the logic of the Rosh? Why don’t we say “k’ein d’Oraisa tikun” to require kashering, even where the fear of intermarriage does not apply?
The Tzitz Eliezer (22:44) addresses this issue in a t’shuvah to Rav Yitzchak Kulitz zt”l, the former Chief Rabbi of Jerusalem. Rav Kulitz suggested that the language of the Rosh/Re’ah is very precise in that they only focus on the reason of intermarriage. In other words, the two reasons for the g’zeirah of Bishul Akum are fundamentally different. The reason forbidding Bishul Akum because we are concerned that the akum added non-kosher food understands that the food cooked by the akum is now viewed as a “chatichah d’isura” – an inherently non-kosher food. On the other hand, the reason forbidding Bishul Akum because we are concerned that it will lead to intermarriage understands that the food is fundamentally kosher, just that the chachamim penalized the Jew for doing this prohibition. The ramification between these understandings is whether the pots need to be kashered. If the food never becomes fundamentally forbidden, the pots don’t need to be kashered.
Rav Kulitz offers an additional ramification: where an akum partially cooks food and the Jew cooks the rest; is the food forbidden? [This happens to be a machlokes between the Shulchan Aruch and the Rama (113:9)]. According to the reason of non-kosher food, yes, the food is forbidden, as the akum turned the item into non-kosher food. However, according to the reason of intermarriage, no, the food is not forbidden, as the Jew is not penalized since he participated in the cooking.
The Tzitz Eliezer, however, strongly disagrees with Rav Kulitz. He notes that the Shulchan Aruch (Yoreh Dei’ah 112:1), by pas akum, is clear that the main reason for the prohibition is because of the fear of intermarriage. Yet, the Shulchan Aruch still rules like the Rashba, that the pots are forbidden. After citing other attacks as well, the Tzitz Eliezer concludes that the machlokes between the Rashba and the Rosh has nothing to do with whether the food itself becomes fundamentally non-kosher, as both opinions hold that it becomes non-kosher. The Tzitz Eliezer does not explain, though, what their machlokes is based upon.
IV. The Sheivet HaLevi’s Slight Difference
The Sheivet HaLevi (11:186) adopts a slightly different rationale for the machlokes between the Rashba and the Rosh. Both the Rashba and the Rosh agree that the main reason for the Bishul Akum prohibition is intermarriage (thus, unintentionally answering the Tzitz Eliezer’s attack on Rav Kulitz). The difference is whether this g’zeirah is on the food (“isur cheftza”) or on the person (“isur gavra”). The Rashba holds that it is on the food; and thus, the pots require kashering. The Rosh holds that it is on the person; and thus, the pots don’t require kashering.
V. Practically Speaking
Practically, we require kashering for any pot used for cooking by an akum, as per the Shulchan Aruch (113:16). The only real leniency is that the Shulchan Aruch adds that an earthenware pot, which normally cannot be kashered, may be kashered if used for bishul akum. We allow hag’alah three times because Bishul Akum is a g’zeirah without any d’Oraisa basis.
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