The 12 th Biblical command is the prohibition of “Kol Mahmeset Lo Tochelu” (Shemot 12:20), which the Rambam understood as a prohibition against eating foods which contain Hametz. The Torah forbids not only eating Hametz directly, but also eating non-Hametz foods with which Hametz had been mixed. The Sefer Ha’hinuch explains that the Torah issued this command to reinforce our commemoration of the miraculous events of the Exodus, when our ancestors were rushed out of Egypt before their dough had a chance to rise, such that they were compelled to eat unleavened bread. We refrain not only from leavened products, but also from mixtures which contain non-leavened products. The Rambam understood that the Torah distinguishes between eating Hametz and eating food into which Hametz had been mixed. One who eats a Ke’zayit of actual Hametz is liable to Karet (eternal excision from the Jewish Nation), whereas, in the Rambam’s view, one who eats food containing Hametz who liable to Malkut (lashes). Specifically, one is liable to punishment if he eats from a mixture which contains Hametz in a proportion of “Ke’zayit Bi’chdeh Achilat Paress” – meaning, one Ke’zayit of Hametz for every “Achilat Paress” (the amount of food one can eat in a period of about 4-9 minutes; the precise definition of “Achilat Paress” is subject to debate). If the Hametz comprises less than this amount of the mixture, then one who partakes of the mixture violates an “Issur De’Rabbanan” (Rabbinic prohibition), as opposed to a Torah prohibition. The Ramban disputes the Rambam’s position. In his view, if a mixture contains Hametz in a proportion of “Ke’zayit Bi’chdeh Achilat Paress,” then eating this mixture is no different from eating Hametz directly. According to the Ramban, there is no separate prohibition forbidding eating this mixture, because a mixture containing this amount of Hametz is no different from actual Hametz, and one who eats this mixture is liable to Karet just like one who eats actual Hametz. The Minhat Hinuch observes that the Rambam distinguishes between eating a mixture containing Hametz and eating actual Hametz also with respect to the time when the prohibition applies. In his introduction to the laws of Hametz on Pesach, the Rambam lists the various Biblical commands that apply to this area of Halacha. He mentions the prohibition against eating Hametz on Ereb Pesach; the prohibition against eating Hametz throughout Pesach; the requirement to eliminate the Hametz from one’s property on Ereb Pesach; and the prohibition against “eating a mixture of Hametz throughout the seven days.” Significantly, the Rambam specifies that eating non-Hametz food which is mixed with Hametz is forbidden (on the level of Torah law) only during the seven days of Pesach, and not on Erev Pesach. It seems that in his view, although the Torah forbids eating Hametz already from midday on Ereb Pesach, it forbids eating Hametz in a mixture only during Pesach itself. On Ereb Pesach, this is forbidden Mi’de’rabbanan – by force of Rabbinic enactment, as opposed to Torah law. Thus, according to the Rambam, a mixture containing Hametz differs from Hametz itself both in terms of the punishment, and also in terms of the timing, as mixtures become forbidden by Torah law only with the onset of Pesach, and not on Ereb Pesach.