What does the evil [son] say? "What is this worship to you?" (Exodus 12:26). 'To you' - and not 'to him.' And since he excluded himself from the community, he denied a principle [of the Jewish faith]. And accordingly, you shall blunt his teeth and say to him, "For the sake of this, did Hashem do [this] for me, when I left Egypt" (Exodus 13:8) - 'For me' and not 'for him.' If he had been there, he would not have been saved.