Exodus 12:13-15

13When you put the blood round the doors of your houses, that will be a sign to show that you live there. When I see the blood on your house, I will pass over you. No trouble will hurt you, when I attack the people of Egypt.

14In future years, you must remember this day as a special day every year. It will be a festival when you worship me, the Lord. You and your descendants must do this every year, for all time.

15For seven days, you must eat flat bread that has no yeast in it. On the first day of the Passover festival, you must take all the yeast out of your houses. During those seven days, if anyone eats bread with yeast in it, he will no longer belong to my people, the Israelites.