The Prohibition to Eat and Benefit From Chametz
The Torah (Shemot 13) states regarding the holiday of Pesach: “Matzot shall be eaten for seven days; neither leaven nor sourdough shall be seen in your borders.”
Our Sages taught in Masechet Pesachim (21b among other places) through expounding certain verses that not only is Chametz prohibited for consumption on Pesach, it is also forbidden to benefit from Chametz on Pesach, meaning that even if one does not actually eat Chametz on Pesach, he still may not sell it to a non-Jew and the like on Pesach for this would mean that he is benefitting from this sale. Consumption of Chametz on Pesach is punishable by Karet (severance of one’s soul from the Jewish nation).
Chametz on Pesach Cannot Even be Nullified by a Ratio of One to One-Thousand
The prohibition of Chametz on Pesach is so severe that if Chametz gets mixed into other foods, it cannot be nullified even by a ratio of one to one thousand, which is not the case regarding other prohibitions.
For instance, regarding the prohibition of consuming blood, if one gram of blood falls into a pot of food, if there are sixty grams of food present against the one gram of blood that fell into it, the blood is considered nullified and this food is permitted for consumption. Regarding Chametz on Pesach, however, even if the food present is one thousand times the amount of the Chametz that fell into it, for instance if a tiny crumb of Chametz falls into a large pot of food, the entire pot of food becomes prohibited for consumption because of the crumb of Chametz that became mixed into it.
Therefore, one must be extremely careful regarding Chametz on Pesach to buy only food products that one is completely certain do not contain Chametz mixtures and are certified by a reliable Kashrut organization. Similarly, one should not rely on a non-Torah-observant Jew when he tells him that a certain food does not contain any Chametz, for instance if he says that a certain spice does not have any Chametz mixed into it, for it has already occurred that some people have transgressed the prohibition of Chametz because they had relied on a grocer with no believability. Maran Harav Ovadia Yosef Shlit”a writes that it is proper for one not to purchase any food product designated for Pesach use without a reliable Kosher for Passover certification on every single item. The same applies even to things that do not seem problematic such as liquor, Arack, and the like. Nowadays, even products that look “innocent” pose major Kashrut problems during the rest of the year and especially during Pesach, as all products contain a multitude of ingredients, as we all know.
Dishes Which Have Absorbed Chametz
One may not use the same dishes that he uses during the rest of the year on Pesach, for these dishes have Chametz absorbed in them since when a hot food is inside these dishes, the walls of these dishes absorb its Chametz flavor, just as they absorb dairy or meat flavor. Thus, one must either use dishes that are specially designated for Pesach that have not been used for Chametz or kosher (make kosher for Pesach) his Chametz dishes. This will be better explained in following Halachot.
The Words of the Saintly Ari z”l and Maran zt”l
We have heard Maran Rabbeinu Ovadia Yosef zt”l quote the words of the saintly Ari z”l that one who is careful regarding Chametz on Pesach is guaranteed not to sin the entire year. Maran zt”l recounted that once, the mother of Hagaon Rabbeinu Akiva Eiger questioned this, for we find many great Torah scholars who are meticulous regarding the prohibitions of Chametz and they nevertheless transgress various sins. Hagaon Rabbi Akiva Eiger answered that the words of the Ari z”l are similar to the words of our Sages in that one who is careful regarding Chametz is guaranteed not to transgress any eating related prohibitions throughout the year but this does not mean one will not sin throughout the year at all.
Maran zt”l adds based on the words of Rabbeinu Nissim that when our Sages promise that one will not sin, this only applies when the sinner is not at fault, i.e. Hashem only protects the righteous, those who are careful regarding Chametz, etc. only from incidents that are not in the individual’s control. However, if the person is slightly at fault, such as if one enters a restaurant that is not under the best Kashrut supervision, one will not merit divine protection and it is possible that one will transgress even sins of forbidden food consumption.
Based on this, Rabbeinu Nissim explains that the reason why King Solomon failed at the end of his life and his wives were able to lead his heart astray was because he tried to outsmart the Torah’s commandment of a king not marrying too many wives, for he claimed, “I will marry many wives and my heart shall not stray from Hashem!” At the end, his wives did indeed lead his heart astray. However, regarding matters about which one is not at fault at all and when one is careful with all his actions, such as the incident with Rabbi Chanina ben Gamliel, Hashem shall protect the individual from all failure.