When you come to the land which Y-H-W-H will give you, as He has spoken, you are to keep this service!

And it will be when your children ask you, "What does this service (mean) to you?"  Then say, "It is a Paschal offering to Y-H-W-H who passed over the houses of the Israelites in Mitzrayim when he struck Mitzrayim but saved our homes."

haggadah Section: -- Four Questions
Source: Exodus 12:25-27