Halakhah sa Mga Bilang 15:20: Mishneh Torah, Rest, Peninei Halakhah, Kashrut, Mishneh Torah, Leavened and Unleavened Bread & Mishneh Torah, Positive Mitzvot

It is permissible to knead a large dough on a holiday. But one who kneads from the eve of a holiday may not separate the challah-tithe on a holiday. However if he kneaded it on the holiday, he separates the challah-tithe from it and gives it to a priest (kohen). And if the dough is impure or the challah-tithe became impure, he may not cook the challah-tithe—since we may only cook on a holiday in order to eat, and this is earmarked for burning. And we may likewise not burn it on a holiday—since on a holiday we may not burn consecrated foods that became impure. [This is] because the burning of consecrated foods that became impure is a positive commandment, as it is stated (Leviticus 7:19), "it shall be burnt in fire"; whereas [not] doing forbidden work that is not for the sake of eating and that which is similar to [it] is a positive commandment and a negative commandment—and a positive commandment does not override [one that is both] a negative and a positive [commandment].

Before performing the commandment, we recite the blessing, "Blessed are You, Lord our God, King of the universe who has commanded us with His commandments and commanded us to separate challah" (the Yemenite custom and that of some Ashkenazim) or "to separate challah terumah" (the Sepharadic custom), or "to separate challah from the dough" (the custom of most Ashkenazim and North African Jews).³There are many customs about the formula of the blessing, and all of them are proper: "To separate challah (Rambam, Mishneh Torah, Laws of First Fruits and other Gifts to Priests Outside the Sanctuary 5:11; Kitzur Shulchan Arukh 35:1; Olat Reiyah, p. 153; Shemirat Shabbat KeHilkhatah 42:12; Derekh Emunah 5:100); "to separate challah terumah" (Ben Ish Chai; Kaf HaChaim 457:9); "to separate challah from the dough" (Rashba; Siddur Beit Yaakov); "to separate terumah" (Shulchan Arukh, Yoreh Deah 328:1; Gra 2); "to separate terumah challah" (Rashal; Chatam Sofer). The root of this discrepancy among customs is that the expression, challah, in the Torah means dough; and we separate terumah (tithe) from it, as it is stated (Numbers 15:20), "The first of your kneading troughs, challah, you should separate [as] tithe." But in the usage of the Sages, the commandment and that which is given to the priest is called challah; and even the tractate that deals with the commandment is called Challah.

The dough for which there is an obligation of [separating] hallah is the dough that the generation of the desert was accustomed to making, as it is stated (Numbers 15:20), "The first of your kneading troughs, challah, you should separate [as] tithe." The "kneading trough" is the dough that they would prepare from the manna that fell in the desert every day for each man, as it is stated (Exodus 16:16), "This is what the Lord has commanded: Each man shall gather his requirement of food; an omer per person, according to the number of your people, shall each man take for those in his tent." They would grind the manna and make it into a dough (Numbers 11:8). And the quantity for each person was a tenth of an ephah, as it is stated (Exodus 16:36), "And the omer is a tenth of an ephah" (Eruvin 83b). But dough that is of a smaller quantity than this is not significant, so it is exempt from challah.