The Power of Chad Gadya:
Sefer Emes Y’Vatyziv relates that he heard the following from Rav Avrohom Simcha Horowitz of Barnov zt”l, who heard it from his grandfather, Rav Eliezer of Zhikov zy”a, who was in Lublin for Pesach, together with his father, the Ropshitzer Rebbe zy”a:
When the Chozeh of Lublin zy”a reached the end of the Haggadah and was about to sing Chad Gadya, he asked his chasidim: “Why do we recite the piyyut of Chad Gadya at the end of the Seder?”
Understandably, everyone remained silent, waiting to hear the Chozeh’s answer to this question. The Chozeh said, “You should know that the angels see the great pleasure Hashem gets from the Seder and the great light it creates in Shomayim. Since they cannot duplicate that, they become very jealous of us. We have to be worried that they might try to harm us and create an ayin hara against us because they are so envious. Therefore, it was decreed that we should recite Chad Gadya because it is a remedy to the ayin hara of the malachim.”
