הלכה אויף דברים 6:20

What does the wise [son] say? "'What are these testimonies, statutes and judgments that the Lord our God commanded you?' (Deuteronomy 6:20)" And accordingly you will say to him, as per the laws of the Passover sacrifice, "We may not eat an afikoman (a dessert or other foods eaten after the meal) after [we are finished eating] the Pesach sacrifice (Mishnah Pesachim 10:8)."