Commentaire sur Houlin 5:5
יוֹם אֶחָד הָאָמוּר בְּאוֹתוֹ וְאֶת בְּנוֹ, הַיּוֹם הוֹלֵךְ אַחַר הַלָּיְלָה. אֶת זוֹ דָרַשׁ שִׁמְעוֹן בֶּן זוֹמָא. נֶאֱמַר בְּמַעֲשֵׂה בְרֵאשִׁית (בראשית א), יוֹם אֶחָד, וְנֶאֱמַר בְּאוֹתוֹ וְאֶת בְּנוֹ (ויקרא כב), יוֹם אֶחָד. מַה יּוֹם אֶחָד הָאָמוּר בְּמַעֲשֵׂה בְרֵאשִׁית הַיּוֹם הוֹלֵךְ אַחַר הַלַּיְלָה, אַף יוֹם אֶחָד הָאָמוּר בְּאוֹתוֹ וְאֶת בְּנוֹ, הַיוֹם הוֹלֵךְ אַחַר הַלָּיְלָה:
L'expression de la loi «un jour», lorsqu'elle traite de l'interdiction d'abattre un animal et ses petits en un [et même] jour, doit être comprise, que le jour et la nuit qui l'ont précédé doivent être comptés ensemble [comme formant un jour]. Car c'est ainsi qu'il a été expliqué par R. Shimon ben Zomah: «Le terme (Genèse 1: 5, Lévitique 22:28) 'un jour' est utilisé dans l'histoire de la création et aussi dans l'interdiction d'abattre un animal et ses petits, pour enseignez-nous que, tout comme dans la Création, le jour a suivi la nuit, il faut donc aussi le comprendre dans ce cas. "
Bartenura on Mishnah Chullin
English Explanation of Mishnah Chullin
This was how Rabbi Shimon ben Zoma expounded (: it says “one day” (Genesis 1:5) in connection with the creation and it also says “one day” (Leviticus 22:28) in connection with “it and its young” Just as the “one day” mentioned in connection with the creation means the day and the night preceding it, so too the “one day” mentioned in connection with “it and its young” means the day and the night preceding it.
This mishnah, which I shall explain here and not below, teaches that when we reckon the day on which an animal was slaughtered, the night goes with the day that follows it. Thus if he slaughtered one animal at night and then the following day he slaughtered its mother or offspring, he has violated the law of “it and its young.” But if he slaughters an animal during the day and then the following night he slaughters its mother or young, he has not violated the law.
The basis for this law are the verses from Genesis 1 that state, “and it was evening and it was morning, the first day,” and so on for each day. These verses imply, to the rabbis, that the day begins with the preceding night. And since the words “one day” are used in the context of creation and in the context of the law concerning “it and its young,” the day is reckoned in the same way for each.