Exodus 12:18-20

¹⁸In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty first day of the month at evening. ¹⁹Seven days shall there be no yeast found in your houses, for whoever eats that which is leavened, that soul shall be cut off from the congregation of Israel, whether he be a sojourner, or one who is born in the land. ²⁰You shall eat nothing leavened. In all your habitations you shall eat unleavened bread.`"