Exodus 12:20

16 On the first day you are to hold a sacred assembly, and another on the seventh day. You must not do any work on those days, except to prepare the meals—that is all you may do.

17 So you are to keep the Feast of Unleavened Bread, for on this very day I brought your divisions out of the land of Egypt. You must keep this day as a permanent statute for the generations to come.

18 In the first month you are to eat unleavened bread, from the evening of the fourteenth day until the evening of the twenty-first day.

19 For seven days there must be no leaven found in your houses. If anyone eats something leavened, that person, whether a foreigner or native of the land, must be cut off from the congregation of Israel.

20 You are not to eat anything leavened; eat unleavened bread in all your homes.”

21 Then Moses summoned all the elders of Israel and told them, “Go at once and select for yourselves a lamb for each family, and slaughter the Passover lamb.

22 Take a cluster of hyssop, dip it into the blood in the basin, and brush the blood on the top and sides of the doorframe. None of you shall go out the door of his house until morning.

23 When the LORD passes through to strike down the Egyptians, He will see the blood on the top and sides of the doorframe and will pass over that doorway; so He will not allow the destroyer to enter your houses and strike you down.

24 And you are to keep this command as a permanent statute for you and your descendants.

Read all of Exodus 12