Thursday, March 29 9:00 pm to midnight — Bdikat ḥametz is a ceremony of searching for leavened bread, instituted in order to ensure that not even the smallest particle of ḥametẓ remains in the house during Passover. The biblical injunction, “Even the first day shall ye put away leaven out of your house” (Ex. 12:15), was interpreted by the rabbis as referring to the eve of Passover, i.e., the 14th of Nisan. The ceremony of bdikat ḥametẓ takes place on the 13th of Nisan (or the 12th if the 13th should be on a Friday). It follows the Ma’ariv prayer immediately after nightfall and before any other kind of activity is undertaken. The ceremony is preceded by the blessing: “Blessed art Thou O Lord our God, King of the Universe, Who hast sanctified us by Thy commandments and commanded us concerning the removal of the leaven.”
By the light of a wax candle, with a wooden spoon and a whisk made of several chicken or goose feathers tied together, the master of the house searches every corner in the house for stray crumbs. Every room into which ḥametẓ may have been brought during the past year has to be searched. Since a blessing must never be recited without good reason, a few crumbs of bread are deliberately left on window sills and in other obvious places. The ceremony of bdikat ḥametz takes precedence even over the study of Torah on that evening. If the husband is not available, the ceremony has to be performed by the wife or another member of the family.
The kabbalistic school of R. Isaac Luria hid ten pieces of bread for bdikat ḥametz. Leaven to the mystics symbolized the ferment of base desires and evil impulses which had to be purged. Upon completion of bdikat ḥametz, the leaven collected is put away in a safe place and the master of the house recites these words: “May all leaven that is in my possession, which I have not observed, searched out or had cognizance of, be regarded as null and be common property, even as the dust of the earth.” On the morning of the 14th of Nisan, no later than 10 A.M., the leaven is burned and a similar Aramaic formula is recited. This observance is called Bi’ur ḥametz – the removal or the burning of ḥametz. The laws concerning bdikat ḥametz are codified in Shulḥan Arukh (OḤ 431 to 445).
From Encyclopedia Judaica