21 You shall make a gift to Hashem from the first yield of your baking, throughout the ages.
may-ray-SHEET a-ri-so-tay-KHEM ti-t’-NU la-do-NAI t’-ru-MAH l’-do-RO-tay-KHEM
כא מֵרֵאשִׁית עֲרִסֹתֵיכֶם תִּתְּנוּ לַיהֹוָה תְּרוּמָה לְדֹרֹתֵיכֶם׃
15:21 You shall make a gift to Hashem from the first yield of your baking
The commandment to separate a portion of dough for the Kohanim, known as challah (חלה), went into effect only once the people entered the Land of Israel. This dough is given to the Kohanim, since they did not receive their own portion of land through which they could sustain themselves. The job of the Kohanim is to educate the people and work in the Beit Hamikdash, thereby providing the Nation with spiritual sustenance. In turn, they are provided with physical sustenance from the portions of the other tribes. Such is one’s existence in Eretz Yisrael – the physical and spiritual are continuously intertwined.