במדבר ט״ו:י״ז-כ״א

בבאכם אל הארץ. מְשֻׁנָּה בִּיאָה זוֹ מִכָּל בִּיאוֹת שֶׁבַּתּוֹרָה, שֶׁבְּכֻלָּן נֶאֱמַר כִּי תָבֹא, כִּי תָבֹאוּ, לְפִיכָךְ כֻּלָּן לְמֵדוֹת זוֹ מִזּוֹ, וְכֵיוָן שֶׁפֵּרֵט לְךָ הַכָּתוּב בְּאַחַת מֵהֶן שֶׁאֵינָהּ אֶלָּא לְאַחַר יְרֻשָּׁה וִישִׁיבָה, אַף כֻּלָּן כֵּן, אֲבָל זוֹ נֶאֱמַר בָּהּ "בְּבֹאֲכֶם" — מִשֶּׁנִּכְנְסוּ בָהּ וְאָכְלוּ מִלַּחְמָהּ נִתְחַיְּבוּ בְחַלָּה (ספרי):

At your coming to the land. This “coming” is different from all the “comings” in the Torah. With all of them it says, “when you come,” “when all of you come.” Therefore, all are learned from each other. Since Scripture specified with one of them that it is only after inheriting and settling, all of them are the same. But with this, it is said, “at your coming.” As soon as they entered it (the land) and ate its bread, they were obligated with the mitzvah of challah.

ראשית ערסתכם. כְּשֶׁתָּלוּשׁוּ כְדֵי עִסַּתְכֶם שֶׁאַתֶּם רְגִילִין לָלוּשׁ בַּמִּדְבָּר — וְכַמָּה הִיא? "וַיָּמֹדּוּ בָעֹמֶר" (שמות ט"ז), "עֹמֶר לַגֻּלְגֹּלֶת" (שם) — תָּרִימוּ מֵרֵאשִׁיתָהּ, כְּלוֹמַר קֹדֶם שֶׁתֹּאכְלוּ מִמֶּנָּה, רֵאשִׁית חֶלְקָהּ חלה אַחַת תרימו תרומה לְשֵׁם ה' (עירובין פ"ג):

[From] the first portion of your doughs. When you knead the amount of dough that you generally knead in the desert — how much is that? “They measured it with an omer,” “An omer per person” (the amount is forty-three and one-fifth eggs) — you shall separate [the terumah-gift] from its first portion. As if to say, ‘before you eat the first portion from it, separate one loaf as a terumah-gift for the sake of Hashem”.’

חלה. טורטי"ל בְּלַעַז:

A loaf. Tortel in Old French.

כתרומת גרן. שֶׁלֹּא נֶאֱמַר בָּהּ שִׁעוּר וְלֹא כִתְרוּמַת מַעֲשֵׂר, שֶׁנֶּאֱמַר בָּהּ שִׁעוּר (ספרי), אֲבָל חֲכָמִים נָתְנוּ שִׁעוּר — לְבַעַל הַבַּיִת אֶחָד מֵעֶשְׂרִים וְאַרְבָּעָה וּלְנַחְתּוֹם אֶחָד מֵאַרְבָּעִים וּשְׁמוֹנָה (חלה ב'):

Like the terumah-gift of the granary. For which no specific amount is required, but not like like the terumah-offering from the tithe, for which a specific amount is required. However, the sages required a specific amount: For the home maker, one twenty-fourth, for the commercial baker, one forty-eighth.

מראשית ערסתיכם. לָמָּה נֶאֱמַר? לְפִי שֶׁנֶּאֱמַר "רֵאשִׁית עֲרִסֹתֵכֶם", שׁוֹמֵעַ אֲנִי רִאשׁוֹנָה שֶׁבָּעִסּוֹת, תַּ"ל מראשית — מִקְצָתָהּ וְלֹא כֻלָּהּ (ספרי):

Of the first portion of your doughs. Why is this said? Because it says, “The first portion of your dough,” I would understand this as the first of the loaves. The Torah therefore teaches, “of the first portion” — part of it, but not all of it.

תתנו לה' תרומה. לְפִי שֶׁלֹּא שָׁמַעְנוּ שִׁעוּר לְחַלָּה נֶאֱמַר "תִּתְּנוּ" — שֶׁיְּהֵא בָהּ כְּדֵי נְתִינָה (שם):

You shall give to Adonoy, as a terumah- offering. As we have not heard of a specific amount for the challah-offering, it says, “you shall give” — it should consist of an amount sufficient for “giving.”