Why Passover Leaven May Not Even Be Used for Benefit

Hezekiah said: From where do we know that leaven on Passover is forbidden for deriving benefit throughout the seven days? As it is said, "And leaven shall not be eaten" - it shall have no permitted manner of eating. The reason is that the Merciful One wrote "shall not be eaten"; had the Merciful One not written "shall not be eaten," it would have implied a prohibition of eating but not a prohibition of benefit. And this differs with Rabbi Abbahu, who said in the name of Rabbi Eleazar: Wherever it is said "it shall not be eaten," "you shall not eat," or "you shall not eat (plural)," both a prohibition of eating and a prohibition of deriving benefit are implied, unless Scripture explicitly specifies for you, as it specified in the case of a carcass - to the resident alien by giving and to the foreigner by selling. But consider leaven, concerning which the Merciful One said "leaven shall not be eaten," and it was taught: Rabbi Yose the Galilean says, be astonished at yourself - how is leaven forbidden for benefit all seven days? It is different there, for it is written, "It shall not be seen belonging to you" - that which is yours it shall be. And the Rabbis hold: that which is yours you may not see, but you may see that which belongs to others and that which is consecrated to the Most High. And the other [Rabbi Yose]: "belonging to you" is written twice. And the other: one refers to a gentile whom you have subjugated and one to a gentile whom you have not subjugated. And the other: "belonging to you" is written three times. And the other: one refers to sourdough and one to leaven, and both are necessary.