This Talmudic passage discusses the need to wait between eating meat and dairy, based on the concern of meat remnants between the teeth. While it does not specify a time, this passage is foundational for later interpretations and codifications of the waiting period.
בְּעָא מִינֵּיהּ רַב אַסִּי מֵרַבִּי יוֹחָנָן: כַּמָּה יִשְׁהֶה בֵּין בָּשָׂר לִגְבִינָה? אָמַר לוֹ: וְלֹא כְּלוּם. אִינִי? וְהָא אָמַר רַב חִסְדָּא: אָכַל בָּשָׂר – אָסוּר לֶאֱכוֹל גְּבִינָה, גְּבִינָה – מוּתָּר לֶאֱכוֹל בָּשָׂר! אֶלָּא כַּמָּה יִשְׁהֶה בֵּין גְּבִינָה לְבָשָׂר? אֲמַר לֵיהּ: וְלֹא כְּלוּם. גּוּפָא, אָמַר רַב חִסְדָּא: אָכַל בָּשָׂר – אָסוּר לֶאֱכוֹל גְּבִינָה, גְּבִינָה – מוּתָּר לֶאֱכוֹל בָּשָׂר. אֲמַר לֵיהּ רַב אַחָא בַּר יוֹסֵף לְרַב חִסְדָּא: בָּשָׂר שֶׁבֵּין הַשִּׁינַּיִם מַהוּ? קָרֵי עֲלֵיהּ ״הַבָּשָׂר עוֹדֶנּוּ בֵּין שִׁנֵּיהֶם״. אָמַר מָר עוּקְבָא: אֲנָא, לְהָא מִלְּתָא, חַלָּא בַּר חַמְרָא לְגַבֵּי אַבָּא, דְּאִילּוּ אַבָּא כִּי הֲוָה אָכֵיל בִּשְׂרָא הָאִידָּנָא, לָא הֲוָה אָכֵל גְּבִינָה עַד לִמְחַר עַד הַשְׁתָּא, וְאִילּוּ אֲנָא – בְּהָא סְעוֹדְתָּא הוּא דְּלָא אָכֵילְנָא, לִסְעוֹדְתָּא אַחְרִיתָא – אָכֵילְנָא.
§ Rav Asi posed a dilemma to Rabbi Yoḥanan: How much time should one wait between eating meat and eating cheese? Rabbi Yoḥanan said to him: No time at all. The Gemara asks: Is that so? But doesn’t Rav Ḥisda say: If one ate meat, it is prohibited for him to eat cheese immediately, but if he ate cheese it is permitted for him to eat meat without delay? Rather, Rav Asi actually asked Rabbi Yoḥanan the following question: How much time should one wait between eating cheese and eating meat? In response to this question, Rabbi Yoḥanan said to him: No time at all. After tangentially citing a statement of Rav Ḥisda, the Gemara discusses the matter itself. Rav Ḥisda says: If one ate meat, it is prohibited for him to eat cheese immediately, as the meat contains fatty substances that stick to one’s mouth and preserve the flavor of meat. But if he ate cheese it is permitted for him to eat meat without delay. Rav Aḥa bar Yosef said to Rav Ḥisda: In the case of meat that is between the teeth, what is the halakha? Are these remnants considered meat to the extent that one may not eat cheese as long as they are in his mouth? In response, Rav Ḥisda read about him the following verse: “While the meat was yet between their teeth” (Numbers 11:33). This verse indicates that even when the meat is between one’s teeth it is still considered meat, and therefore one may not partake of cheese until that meat has been removed. Mar Ukva said: I am, with regard to this matter, like vinegar, son of wine, with respect to Father, i.e., my practice is inferior to that of my father. As Father, if he were to eat meat at this time, would not eat cheese until tomorrow at this time. But as for me, only at this meal, during which I ate meat, do I not eat cheese; at a different meal on the same day I will eat cheese.