Before beginning to search for ĥametz, one recites the berakha “Who sanctified us with His mitzvot and commanded us concerning bi’ur ĥametz” (“asher kideshanu be-mitzvotav ve-tzivanu al bi’ur ĥametz”).Though the actual bi’ur ĥametz will not take place until the following morning with the burning and nullification of ĥametz, we nonetheless recite “al bi’ur ĥametz” before the search on the night of the fourteenth, because bedikat ĥametz is the first step in the process of eliminating ĥametz from the home.
After the berakha, it is forbidden to talk before beginning the search. If at this point one talks about matters unrelated to bedikat ĥametz, he has abandoned that berakha and must recite another. If, however, one talks about unrelated matters after beginning the search, his berakha remains valid, for it applies to the portion of the search that was already carried out. One should preferably avoid talking about unrelated matters during the search, in order not to become distracted (SA 432:1; MB ad loc. 5, 6).
One who owns several houses must search them all. He recites the berakha before searching in the first location. He recites it only once, even if the houses are located a distance from one another.
If one must travel, and therefore performed bedikat ĥametz before the fourteenth of Nisan, even though his search is valid, he does not recite the berakha. One only recites the berakha over a search performed from the night of the fourteenth onward, because such a search is adjacent to bi’ur ĥametz. Any ĥametz found on the evening of the fourteenth will be destroyed the next morning. If one was unable to search on the evening of the fourteenth, and instead searched the following day, or during Pesaĥ, he recites the berakha, because he will immediately destroy any ĥametz he finds, and it is appropriate to recite “albi’ur ĥametz” over such a search. But if one searches before the fourteenth, he does not recite the berakha (Rema 436:1 and BHL ad loc.; MB 435:5).
.If one forgot to make the berakha before the bedika and remembered while in the middle, as long as he has other areas to check, he may still make the berakha. However, if he remembered after the completion of the bedika, the poskim disagree about whether he can make the berakha before burning the ĥametz the following day. According to MB 432:4, we do not prevent someone from making the berakha in this situation, since the berakha is on the burning of the ĥametz; thus, as long as he has not yet burned the ĥametz, he can make the berakha. On the other hand, there are those who hold that the Sages enacted the berakha on the bedika and not on the burning, and therefore if one forgot to make the berakha by the end of the bedika, he has lost his opportunity to do so. This is the opinion of Baĥ, SAH, and others. When in doubt about whether or not to make a berakha, we are lenient, and so one should not make the berakha. One should not make a berakha on bitul ĥametz alone, since we do not make berakhot on mere words or thoughts.
.The authorities disagree about this, as noted in MB432:7. According to Pri Ĥadash and Ĥayei Adam, walking a far distance is considered a significant interruption, and he would have to make a new berakha. Conversely, according to Ĥok Yaakov and Ma’amar Mordechai, walking is not considered a significant interruption. This is also the opinion of Kaf Ha-ĥayim 432:22. When in doubt about whether or not to make a berakha, we are lenient. The Aĥaronim also disagree about whether a shali’aĥ appointed to search part of a house who did not hear the owner’s berakha must make his own berakha; see SHT 432:9.
. Indeed according to Ra’ah and Pri Ĥadash, one who is halakhically required to check should make a berakha, since the purpose of the bedika is to ensure that he does not violate bal yeira’eh/bal yimatzei afterward; since the Sages decreed that one who leaves his house before the night of the fourteenth should check before he leaves, he should also make a berakha. According to Ritva and Baĥ, he should make the berakha as long as he checks within the thirty days before Pesaĥ. But, as noted, Kol Bo and Rema (436:1) are of the opinion that the berakha is also on the burning that takes place the following morning. This is also the opinion of Gra, and seems to be the conclusion of MA, Taz, and others. If one is uncertain about the berakha, we are lenient, and this seems to be the opinion of BHL ad loc.
Itur states that there are those who maintain that one must also make the berakha of “she-heĥeyanu” prior to the bedika, since it is a mitzva that comes periodically, and there are those who say not to recite this berakha. Rosh rules that one should not make this berakha, since the bedika is connected to the Pesaĥ holiday, when anyway he will recite she-heĥeyanu. Shulĥan Arukhdoes not even mention the idea of she-heĥeyanu on the bedika. However, some Aĥaronim suggest, as a nice custom, that one take a new fruit or new garment and recite she-heĥeyanu on it before the bedika (Kaf Ha-ĥayim 432:9).