מתני׳ הלוקח כלי תשמיש מן העובדי כוכבים את שדרכו להטביל יטביל להגעיל יגעיל ללבן באור ילבן באור השפוד והאסכלא מלבנן באור הסכין שפה והיא טהורה:
MISHNA: One who purchases cooking utensils from the gentiles must prepare them for use by Jews in the following manner: With regard to those utensils whose manner of preparation is to immerse them in a ritual bath, as they require no further preparation, he must immerse them accordingly. With regard to those utensils whose manner of preparation is to purge them with boiling water, as those utensils are used with boiling water, e.g., pots, he must purge them accordingly. With regard to those whose manner of preparation is to heat until white-hot in the fire, as they are used for grilling, he must heat them until white-hot in the fire. Therefore, with regard to the spit [hashappud] and the grill [veha’askela], he must heat them until white-hot in the fire. With regard to the knife, he must polish it and it is rendered pure.
הסכין שפה והיא טהורה: אמר רב עוקבא בר חמא ונועצה עשרה פעמים בקרקע אמר רב הונא בריה דרב יהושע ובקרקע שאינה עבודה א"ר כהנא ובסכין יפה שאין בה גומות תניא נמי הכי סכין יפה שאין בה גומות נועצה עשרה פעמים בקרקע אמר רב הונא בריה דרב יהושע לאכול בה צונן
§ The mishna teaches: With regard to the knife, one must polish it and it is rendered pure. Rav Ukva bar Ḥama says: And one must thrust it ten times into the ground. Rav Huna, son of Rav Yehoshua, says: And this must be done in untilled earth, i.e., hard earth. Rav Kahana says: And this applies to a good knife that does not have notches, so that the entire surface of the knife is scraped against the ground. This is also taught in a baraita: With regard to a good knife that does not have notches, one can thrust it ten times into the ground. Rav Huna, son of Rav Yehoshua, says: This is sufficient for the purpose of eating cold food with it.
כי הא דמר יהודה ובאטי בר טובי הוו יתבי קמיה דשבור מלכא אייתו לקמייהו אתרוגא פסק אכל פסק והב ליה לבאטי בר טובי הדר דצה עשרה זימני בארעא פסק הב ליה למר יהודה א"ל באטי בר טובי וההוא גברא לאו בר ישראל הוא א"ל מר קים לי בגויה ומר לא קים לי בגויה
This is like that incident involving Mar Yehuda, an important personage of the house of the Exilarch, and Bati bar Tuvi, a wealthy man, who were sitting before King Shapur, the king of Persia. The king’s servants brought an etrog before them. The king cut a slice and ate it, and then he cut a slice and gave it to Bati bar Tuvi. He then stuck the knife ten times in the ground, cut a slice, and gave it to Mar Yehuda. Bati bar Tuvi said to him: And is that man, referring to himself, not Jewish? King Shapur said to him: I am certain of that master, Mar Yehuda, that he is meticulous about halakha; but I am not certain of that master, referring to Bati bar Tuvi, that he is meticulous in this regard.
איכא דאמרי א"ל אידכר מאי עבדת באורתא:
There are those who say that King Shapur said to him: Remember what you did last night. The Persian practice was to present a woman to each guest, with whom he would engage in intercourse. Mar Yehuda did not accept the woman who was sent to him, but Bati bar Tuvi did, and therefore he was not assumed to be meticulous with regard to eating kosher food.