EXOD177 Although Judaism believes that action and not the spoken word is what usually fulfills the commandments, there are some mitzvot that are so important that words must accompany the action. Therefore, on Passover night, it is not sufficient merely to eat the matzo and marror or to drink the wine, but Rabban Gamliel says Pesachim 116a that these actions must be accompanied by words showing understanding of the actions and symbols. Later on, this requirement of words was incorporated into the Haggadah itself and was then codified as Jewish law. Maimonides, Hilchot Chametz Umatzah 7:5. This is part of the general mitzvah on Passover eve to tell again the story to one's children.