Fermenting dough ( = "to be sour," "fermented"; Aramaic, ). Leavened bread was probably a common article of food among the ancient Israelites (Hos. vii. 4), while unleavened bread ("maẓẓot") was prepared when food was required at short notice (Gen. xix. 3; I Sam. xxviii. 24). Such bread was designated "the bread of affliction," because of its association with Egyptian slavery (Deut. xvi. 3; Ex. xii. 34-39; see Baking; Bread; Maẓẓah). With few exceptions (Lev. vii. 13, xxiii. 17), leaven was forbidden in sacrificial offerings (Ex. xxiii. 18, xxxiv. 25; Lev. ii. 11, vi. 10; comp. Amos iv. 5; see Sacrifice). In later times, "leaven" and "corruption" were regarded as synonymous terms (Matt. xvi. 6-12; Mark viii. 15; I Cor. v. 6-8). The Rabbis, in speaking of the evil desire ("yeẓer ha-ra'"), called it "the leaven that is in the dough" (Ber. 17a; comp. Gen. R. xxxiv. 12; Yalḳ., Ruth, 601), and the term was thus extensively used by the cabalists of the Middle Ages (Hastings, "Dict. Bible," s.v.).
During the festival of Maẓẓot it was strictly forbidden to eat anything leavened, or even to keep such food on one's premises (Ex. xii. 14-20, xiii. 3-7, xxiii. 15, xxxiv. 18; Lev. xxiii. 6; Num. xxviii. 17; Deut. xvi. 3, 4). The punishment for eating leavened bread during these seven days was "karet" (Ker. 2a), and for preparing it, stripes (Maimonides, "Yad," Ḥameẓ, i. 1-3). The reason for this prohibition is given in Ex. xii. 34-39, although other reasons have been advanced by modern scholars (see Maẓẓah; Passover).Kinds of Leaven.
With reference to this prohibition three kinds of leaven were distinguished by the Rabbis: (1) leavened food prepared from the five kinds of grain, wheat, barley, oats, corn, and spelt ("ḥameẓ gamur"); (2) food in which leaven of the first kind was mixed ("ta'arubot"); and (3) any leavened substance unfit for food, e.g., the dough which the cooks used to place over the pot or that which the bookbinders used for pasting the leaves ("ḥameẓ nuḳsheh"). Leaven of the first kind carried with it the punishment of karet; of the second, stripes; while that of the third kind, being prohibited only by a rabbinical decree, carried no punishment with it (Pes. 43a; "Yad," l.c. 6; Shulḥan 'Aruk, Oraḥ Ḥayyim, 442, 1; Ḥayye Adam, 121, 1).Sale of Leaven to Gentiles Before Passover.
An Israelite may not derive any benefit from unleavened bread during Passover. He may not feed his animal with it, nor may he burn it and then make use of the fire (Pes. 5b, 21b). The Rabbis, in order to punish him who did not remove all leaven from his house before the holy day, went still further in their restrictions, and decreed that the use or benefit from any leaven belonging to an Israelite left over after the holyday was forever prohibited (ib. 28a, 29a; "Yad," l.c. i. 4). If, however, the Israelite had sold or given all his leaven to a non-Jew before Passover, it might be bought back and used by the Jew after Passover (Tosef., Pes. ii. 5, 6; Rosh, ib. ii. 4). It has thus become customary for one who has much leaven left to sell it to a non-Jew before Passover. A contract is drawn up in legal form in which all the details are set forth, and earnest-money is accepted; and the key of the room in which the leaven is stored up is delivered to the non-Jew. A common custom, followed by a great many communities, is for all the Jews of the town to make the rabbi the agent for selling all their leaven to a non-Jew. A few days before the festival every Israelite comes to the rabbi's house and signs a deed of sale and enters into the symbolical form of sale ("ḳinyan") with the rabbi; and then the rabbi draws up a separate deed for the non-Jew, to whom all the other deeds are delivered. It is also necessary to rent to the non-Jew the room in which the leaven is stored (Sha'are Teshubah to Oraḥ Ḥayyim, 448, 3; Ḳiẓẓur Shulḥan 'Aruk, 114).
If a particle of leaven fall into a boiling pot during Passover, even though the pot contain more than sixty times the amount of leaven, all the food in the pot is prohibited, and the pot itself can not be used again during the festival (Pes. 30a; "Yad," l.c. i. 5). If, however, the leaven fall into the pot before Passover, and the amount in the pot is sixty times the amount of leaven, the food may be eaten on the festival. Dishes or pots which have been used during the year for articles containing leaven can not be used during the festival, unless they have gone through some process of purification. Earthenware vessels which have been used for leaven must be burned again in the potter's kiln, while vessels made of metal may be used after they have undergone a process of purification("hag'alah"). Vessels used on the fire, such as spits or broilers, must be made red hot before they can be used for Passover, while vessels that have been used in cooking, such as pots and pans, must be boiled in water ('Ab. Zarah 75b; Rosh Pes. ii. 7; "Yad," l.c. v. 21-26; Oraḥ Ḥayyim, 451). Dishes, spoons, and forks are made fit for use on Passover by pouring hot water over them. The custom, however, is to have these as well as all vessels, even such as have been used only for cold food or drink, boiled in the same manner as vessels used in cooking. Large vessels, such as can not be placed in other vessels in order to have them boiled, can be purified by being passed over a hot stone while hot water is being poured over them (Oraḥ Ḥayyim, 451, 6, and Isserles' note). Wooden tables upon which hot vessels containing leaven have been placed should bescrubbed with hot water, and, as is usually the custom, rubbed over with a hot stone. Polished tables which can not be washed in this manner must be covered with heavy cloth for Passover, so that the heat of the dishes placed upon them shall not reach the surface (Oraḥ Ḥayyim, 451, 20, and Be'er Heṭeb, ad loc.). Some rabbis are of the opinion that glassware needs no special purification for Passover; others, that no process of purification can make it fit for use (ib. 26, and "Magen Abraham," ad loc.). In some countries it is the custom to leave glasses in water for three successive days, changing the water every day, in order to make them fit for use on the festival (Ḥayye Adam, 125, 22). In order to avoid all doubt, observant Jews provide themselves with separate sets of dishes and kitchen utensils for Passover, which are stored away from year to year, being used only during the festival.Search for Leaven Before Passover.
Many days before Passover the pious Jewish housewife commences her house-cleaning for the festival. On the eve of the fourteenth of Nisan, although most Jewish houses are then thoroughly free from all leaven, the master of the house proceeds with the ceremony of searching for leaven ("bediḳat ḥameẓ"; Pes. 2a; see Bediḳah). Pieces of bread are placed in conspicuous places which can not be overlooked, and with a wax candle in his hand the master of the house begins the search, after pronouncing the following blessing: "Blessed art thou . . . and commandest us concerning the removal of leavened bread" (ib. 7b). After he has searched all the rooms and has collected all the morsels of leaven in a wooden spoon, he carefully ties them up in a rag and stores them away in a place which can not be reached by rats, pronouncing the following formula in Aramaic or in any language which he understands best: "Let all leaven that is in my premises which I have not seen and which I have not removed be as of no avail and be as the dust of the ground." On the next morning leaven may be eaten only until the fourth hour of the day (ib. 12b); and soon after that time all the remaining leaven is carefully collected and burned, when the master of the house repeats the formula, with a few alterations, which he recited on the previous evening (Oraḥ Ḥayyim, 431-437).
Any leaven found in the house during Passover, if discovered on the week-days of the holy day, should be immediately burned; if found on the holy day itself it should be covered with a vessel and burned in the evening. While it is being burned the above-mentioned blessing should be pronounced (Pes. 6a; "Yad," l.c. iii. 8; Oraḥ Ḥayyim, 446).