What makes the prohibition of Hamets so unique is that, unlike other forbidden foods, it also includes the ban of its possession. There are two Mitsvot in the Tora related to the prohibition of possessing Hamets: 1. bal year-e (lit. your Hamets shall not be seen in your premises); 2. bal-yimatse (Hamets shall not be found in your premises). Our Rabbis explained that these two Mitsvot actually point out to one single prohibition: owningHamets during Pesah. Ownership or possession is a legal, abstract concept. If I posses Hamets during Pesah, even if that Hamets is stored outside my premises, I would be violating these two Biblical Mitsvot. In addition, we also have a third Mitsva called 3. tashbitu (you shall end the possession of your Hamets), which commands us to actively disown our Hamets before Pesah begins. In sum, owning Hamets during Pesah would imply the violation of these three commandments.
Strictly speaking, (and following Maimonides opinion) these three Mitsvot are fulfilled at once by the bitul , i.e., a formal verbal declaration by which we renounce to the ownership of any eatable Hamets (non-eatable Hamets is not under the prohibition of benefit or ownership), which knowingly or unknowingly, belong to us, regardless of where that Hamets is located.
But the Rabbis explained that if we would only perform this verbal renunciation to our Hamets while keeping it in our possession we might face some practical problems. First, we might be declaring that we do not own anymore our Hamets, while at the same time, if we posses any valuable Hamets (imagine an expensive whiskey bottle), would we really and wholeheartedly mean that we renounce for good to its possession? Probably not. So, the bitul would become an insincere declaration of renunciation to our valuable Hamets. Second problem: Hamets (bread, crackers, cookies, etc.) is one of the most common foods. Therefore, if we renounce to our Hamets but we still keep it at home, we might eat it accidentally during Pesah...
This is why our rabbis instructed that before we do the bitul, we should physically get rid of any eatable Hamets we own, before Pesah begins.
Accordingly, and following Talmudic tradition, there are four steps that should be taken to properly cover these three Biblical commandments.
(1) We should clean our houses, cars, offices, etc. before Pesah begins, to remove all Hamets from our premises.
(2) We have to run a final search of all our properties to make sure that we have removed everything Hamets from them (בדיקת חמץ).
(3) We have to physically remove and get rid of any Hamets found in our properties before and during the Bediqa (ביעור חמץ).
(4) Then, we declare that whatever Hamets we may still own, which was not detected or removed by us, does not belong to us anymore, and from now on that Hamets is considered ownerless (הפקר) as the dust of the earth ( ביטול חמץ).
B'H, in the coming days, we will explain each one of these steps in more detail.