Exodus 12
14 Ref And this day shall be unto you for a memorial, and ye shall keep it a feast to Jehovah: throughout your generations ye shall keep it a feast by an ordinance for ever.
15 Ref Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.