The Ten Pieces of Chametz
There is a widespread custom to "hide" ten pieces of chametz throughout the home before one begins the bedikat chametz.[1] This custom evolved primarily in order to offset the concern that the blessing recited before the bedika would be in vain if no chametz were to be found. Nevertheless, the mitzva is not to find chametz but rather to search for it. As such, even if no chametz is found during the search the blessing would not have been in vain.[2] Indeed, the blessing recited before performing the bedikat chametz refers not to the searching or finding of chametz, but more precisely, to the burning of chametz, which actually takes place the next morning.
It is interesting to note that some authorities have called the custom of hiding ten pieces of bread "baseless" and the "custom of fools".[3] Further evidence that hiding ten pieces of chametz is unnecessary is the fact that one who for whatever reason did not perform the bedikat chametz before Pesach, must do so during Pesach – at which time hiding ten pieces of chametz is simply not an option![4] As such, it is also suggested that the reason for hiding ten pieces of chametz before the bedika may have been a result of emotional frustration that one might experience if no chametz were to be found at all. By extension, it might just be that hiding the ten pieces of chametz was an incentive to ensure that a proper and thorough search would be performed.
In other families and communities there is no such custom and no chametz is hidden prior to the bedikat chametz.[5] Among the reasons for this approach is the concern that, in the event that the ten hidden pieces were not all found, one might be in violation of the prohibition of having chametz in one's possession over Pesach! Either way, one must not deviate from one's family custom.[6]
Those who do hide ten pieces of bread (or other chametz) should ensure that the pieces are small, preferably less than one ounce each. This is because should any of the hidden pieces not be found during the bedika, one will not be in violation of the prohibition to possess chametz on Pesach with such a small amount.[7] Similarly, there is no requirement to search one's home for chametz of this size.[8] In any event, smaller pieces burn better.[9]
The pieces of chametz can be hidden by the one who will be conducting the bedika or by other members of the household.[10] One who is going away for Pesach must do the bedikat chametz the night before one's departure. In such a situation, there is no obligation to hide ten pieces of chametz even if one's custom is ordinarily to do so.[11]
The kabbalists speak of a custom to sprinkle salt upon the ten pieces of chametz which are found during the bedika and to keep them exposed on a plate overnight. This is said to be effective in warding off the Satan and other negative forces whose jealousy is aroused when they see the Jewish people preparing for Pesach and ridding their homes of chametz with love and devotion.
[1] Rema, OC 432:2.
[2] Rema, OC 432:2; Mishna Berura 432:13.
[3] Tamim Deim 29.
[4] Rambam, Hilchot Chametz U'matza 3:6; OC 435:1.
[5] Taz, OC 432:4; Shaar Hatziun 432:11.
[6] Chok Yaakov, cited in Bishvilei Haparasha p.171.
[7] Shaarei Teshuva, OC 432:3.
[8] Machzik Bracha 432, 439.
[9] Tzuf Dvash 67.
[10] Piskei Teshuvot 432:4.
[11] Minchat Yitzchak 8:35.