Exodus 34:18

“This month shall be the beginning of months for you; it is to be the first month of the year to you.

‘Seven days you shall eat unleavened bread, but on the first day you shall remove leaven from your houses; for whoever eats anything leavened from the first day until the seventh day, that person shall be cut off from Israel.

‘Seven days there shall be no leaven found in your houses; for whoever eats what is leavened, that person shall be cut off from the congregation of Israel, whether he is a sojourner or a native of the land.

It is a night to be kept for Yahweh for having brought them out from the land of Egypt; this night is for Yahweh, to be kept by all the sons of Israel throughout their generations.

“This day, in the month of Abib, you are going out.

‘Then on the fifteenth day of the same month there is the Feast of Unleavened Bread to Yahweh; for seven days you shall eat unleavened bread.

‘And on the fifteenth day of this month shall be a feast; unleavened bread shall be eaten for seven days.

“You shall not eat leavened bread with it; seven days you shall eat with it unleavened bread, the bread of affliction (for you came out of the land of Egypt in haste), so that you may remember the day when you came out of the land of Egypt all the days of your life.