Exodus 12:21-28

21Then Moses called for all the elders of Israel and said to them, “Go, select lambs for your families and slaughter the Passover lamb.

22You are to take a bundle of hyssop, dip it in the blood that is in the basin, and apply it to the crossbeam and two doorposts with the blood from the basin. None of you may go out the door of his house until morning.

23Adonai will pass through to strike down the Egyptians, but when He sees the blood on the crossbeam and the two doorposts, Adonai will pass over that door, and will not allow the destroyer to come into your houses to strike you down.

24Also you are to observe this event as an eternal ordinance, for you and your children.

25“When you come into the land which Adonai will give you as He has promised, you are to keep this ceremony.

26Now when it happens that your children ask you, ‘What does this ceremony mean to you?’

27You are to say, ‘It is the sacrifice of Adonai’s Passover, because He passed over the houses of Bnei-Yisrael in Egypt, when He struck down the Egyptians, but spared our households.’” So the people bowed their heads and worshipped.

28Then Bnei-Yisrael went and did it. They did just as Adonai had commanded Moses and Aaron.