The Yerushalmi (quoted in Tosfos, Rosh Hashanah 16.) states, "When the Satan hears the shofar [on Rosh Hashanah] for the first time, he becomes somewhat afraid (בהיל ולא בהיל). When he hears the shofar again, the Satan says, 'This is certainly the great shofar of Moshiach. I will be destroyed.' He becomes confused and is unable to speak kitrug (slander) on the Jewish people."
The Bardichover Rav zt'l said that cleaning for Pesach creates similar malachim as are created by blowing the shofar. Therefore, we can say that when women clean their homes for Pesach, the Satan becomes somewhat afraid (בהיל ולא בהיל). But when a child comes into the house carrying chametz in his hands, and nevertheless, the parents are careful not to become angry, this is like the second set of blasts of the shofar. The Satan becomes very afraid. Due to his fear, he can’t speak kitrug against the Jewish people.
A renowned mechanech and tzaddik from Yerushalayim invited some of his students to his home for the Seder. The students were shocked when they entered his house and found a very non yom-tovdig atmosphere. They found the home turned over, and there was no sign that it was the Seder night. (Unfortunately, the wife of this renowned mechanech was emotionally unwell, and things like this would happen in his home.)
Their host told them, "When you go to other people's homes and find the table set, the children dressed in their yom tov clothing, pleasant aromas coming from the kitchen, you think you see freedom. I say you are seeing slavery because they are enslaved to that perfect situation. If a minor detail is out of order, the family doesn’t know how to handle it. But in this home, we celebrate true freedom because we accept Hashem's will, whatever it is. If this is what Hashem wants, it is good for us."
Every year, before the Seder, the married children of Reb Zalman Brizel zt'l would come with their families to wish him a gut yom tov. One year, one of the grandchildren accidentally threw down all the matzos. Reb Zalman didn’t become upset. He exclaimed, "Hashem gave me grandchildren. Isn't that a reason to be happy?"
