If one is not sure whether he blew the shofar, should he say a brocha when he blows?

If a person is not sure whether he is required to do a mitzvah min haTorah, the halacha is that he must do the mitzvah. Uncertainty in this case includes the question of whether one is obligated in the mitzvah as well as doubts about whether one had already done the mitzvah. Another example of uncertainty involves situations where a Torah mitzvah was supposed to have been done during the day, but it is already bein hashmoshos. The rationale behind the obligation to perform the mitzvah in these cases is sfeika d’oraisa l’chumra (one must be stringent in cases of doubt regarding Torah obligations). Brochos on a mitzvah are only a Rabbinic obligation. Based on the rule of sofek d’rabonon l’kula (one should be lenient in cases of doubt regarding Rabbinic obligations), it would follow that a brocha should not be said when one is in doubt about it. Some Achronim say that in a case when one is doing a mitzvah min haTorah because he is unsure about whether he has already done the mitzvah, he should say a brocha. They explain that since the person knows he is obligated but is not sure if he has already met his obligation, there is strong reason to believe that he has not done the mitzvah. Other Achronim do not agree with this distinction.

ס"ק א; ביאורים ומוספים דרשו, 3-1

What must be repeated if a person is not sure whether he said Shema?

If a person is not sure whether he recited Kriyas Shema and its brochos, Shulchon Aruch rules that he must recite both Shema and the brochos. The obligation to recite the parts of Shema which are a Torah obligation is based on the rule of sofek d’oraisa l’chumra. The reason why the rest of Shema and the brochos must be said is based on the edict of Chazal that when there is an obligation to say a part of Shema, one must say it in its entirety, along with its brochos. The obligation to repeat Shema and brochos applies even if one is certain that he said the parts which are min haTorah. Some Achronim disagree with the Shulchon Aruch’s ruling regarding the obligation to repeat the brochos.

סעיף א, ס"ק ג-ד, וביה"ל ד"ה ספק; ביאורים ומוספים דרשו, 14 ;וראה עוד ס"ק ג

When is one obligated to mention yetzias Mitzrayim?

There is a Torah obligation to mention yetzias Mitzrayim once during the day and once at night. Although this mitzvah can be done any time throughout the day by saying any pasuk or halacha related to yetzias Mitzrayim, Chazal instituted that it should be performed before the end of zman Kriyas Shema when saying the third parsha of Shema. One can also be yotzei his obligation when saying the brochos of Emes V’yatziv and V’Emunah. In a case when a person is unsure whether he said the third parsha of Shema and the following parsha, the poskim disagree about how to proceed. Some say to say the parsha and the Emes V’yatziv, while others hold that only the parsha should be said.  At night, one should say the brocha of V’emunah and not the third parsha.

ס"ק ג-ד

• It is forbidden to interrupt between geulah and tefilah--even to respond to Kaddish and Kedusha. If one has not yet responded to either and he anticipates that the tzibur will reach Kaddish or Kedusha when he reaches Shemoneh Esrei, he should pause at Shira Chadosha so that he can respond with the tzibur.

• Some Rishonim hold that it is not necessary to connect geulah and tefilah on Shabbos. Although one should be stringent, he may respond to Kedusha and Kaddish. Since there are opinions that allow one to respond even during the week, one may rely on their view on Shabbos.

• The Talmud Yerushalmi teaches that there are four important concepts included in the brocha of Emes V’yatziv: Malchus Hashem, yetzias Mitzrayim, krias Yam Suf and makas bechoros.  

• Is it necessary to say an entire brocha?

• Can a person change his nusach?

• May one follow a nusach other than the tzibur’s?