This hints to us that when we prepare for Pesach, we should be cautious of anger, which is a type of avodah zarah. As Chazal say, "Whoever becomes angry, you should consider it like he worshipped avodah zarah."
Tzaddikim say that women could attain ruach hakodesh when they clean for Pesach; only anger prevents it from occurring. Once at the seder of Rebbe Yochanan of Tolna zt'l, the rebbe's young grandson came into the dining room carrying a beer bottle. The family was shocked. "Chametz by the seder?"
(The child had taken the beer from the closet sold for Pesach.)
Everyone lost their calm, except for the Rebbe. The Rebbe told the young boy to put down the bottle, and he covered it with a pot. He did so with joy, to perform the halachah (Pesachim 6): “If one finds chametz on Pesach, he should cover it with a utensil.” After covering the beer bottle with a pot, he placed a small tablecloth over it so it would appear respectable in honor of Yom Tov. He said to his grandson, "Thank you so much! You enabled us to keep a halachah in Shulchan Aruch. How often does one have the opportunity to keep the halachah of covering chametz? This halachah wasn’t given to Goyim; it was written for Yidden, and it is seldom that we get to keep it. You helped us fulfill it."
Others would have responded with anger. But what would anger accomplish? It wouldn’t enhance the Yom Tov atmosphere, and it wouldn't increase the child's love for mitzvos. It wouldn’t do much for the child’s self-esteem, either. Rebbe Yochanan showed him the joy in keeping halachah, the pleasure of Yiddishkeit, and that is a positive lesson that can last for years to come.
