Halakhah for Berakhot 2:3
הַקּוֹרֵא אֶת שְׁמַע וְלֹא הִשְׁמִיעַ לְאָזְנוֹ, יָצָא. רַבִּי יוֹסֵי אוֹמֵר, לֹא יָצָא. קָרָא וְלֹא דִקְדֵּק בְּאוֹתִיּוֹתֶיהָ, רַבִּי יוֹסֵי אוֹמֵר יָצָא, רַבִּי יְהוּדָה אוֹמֵר לֹא יָצָא. הַקּוֹרֵא לְמַפְרֵעַ, לֹא יָצָא. קָרָא וְטָעָה, יַחֲזֹר לְמָקוֹם שֶׁטָּעָה:
One who recites the Shema without causing himself to hear it fulfills the obligation. R. Yossi says: He does not fulfill the obligation. [For it is written (Deuteronomy 6:4): "Hear" — Let your ear hear what your mouth utters. And the first tanna holds: "Hear" — in any language that you are accustomed to hear. And the halachah is according to the first tanna.] If he recited it without being precise with its letters [to enunciate them clearly, in an instance of two words where the second word begins with the same letter with which the first letter ends, as in "al levavcha," "esev besadecha," "va'avadetem meherah." If he does not leave space between them to separate them, it sounds as if he is pronouncing two letters as one.] — R. Yossi says: He has fulfilled his obligation. [And the halachah is according to R. Yossi. However, ab initio, he must enunciate the letters. Likewise, he must take care not to rest the mobile sheva and not to move the quiescent, and not to weaken (by pronouncing without a dagesh) a strong form and not to strengthen a weak one. And he must accentuate the zayin of "tizkeru," so that it does not sound like "tiskeru," that is, "so that you amass reward." For it is not fitting to serve the Master for the sake of reward.] R. Yehudah says: He has not fulfilled his obligation. If one recites it in inverted order [If he recites the third verse before the second, the second before the first, and the like], he has not fulfilled his obligation [it being written (Deuteronomy 6:6): "and these words shall be" — they shall remain in their original form, i.e., as they are ordered in the Torah. However, if he advances the section, reciting vayomer before vehaya im shamoa, and vehaya im shamoa before Shema, it would seem that this is not considered "inverted," and he fulfills his obligation; for they are not thus arranged, one after the other, in the Torah.] If he recited it and erred, he returns to the point of the error. [If he erred between one section and another, not knowing with which section he left off and to the beginning of which section he should return, he returns to the first verse, vehaya im shamoa. (Rambam says: Veahavta eth Hashem.) And if he stopped in the middle of a section, knowing which section, but not knowing where in that section he left off, he returns to the beginning of that section. If he recited "uchethavtam," but did not know whether it were that of Shema or that of vehaya im shamoa, he returns to the "uchethavtam" of Shema. And if he were in doubt after he began leman yirbu, he does not return, for he can rely on "the habit of his tongue."]
Peninei Halakhah, Women's Prayer
MA explains that if women had been obligated by the Torah to wear tefilin, the rationale that they are not careful about cleanliness would not exempt them from the mitzva. However, since they are exempt and there is a concern about cleanliness, their wearing tefilin is objectionable. Along these lines, AHS states that really men have the same problem; tefilin require a clean body. However, since men are obligated, they wear tefilin for Shema and prayers while being as careful as possible. Women, though, are exempt, and should not subject themselves to this serious concern. For them, the time of prayer and reciting Shema are the equivalent of the rest of the day for men. We therefore do not allow them to wear tefilin. Even though Michal wore tefilin and the Sages did not object, this case is not instructive. Presumably, they knew that she was completely righteous and knew how to take the proper precautions. Similarly, Kaf Ha-ḥayim 38:9 states in the name of Birkei Yosef and other Aḥaronim that one should object to women wearing tefilin and cites esoteric reasons for this as well.
Yet there are Rishonim who say that one should not object. Indeed, Orḥot Ḥayim challenges Maharam’s strict ruling (cited in Kol Bo) based on the opinion that the Sages did not object to Michal wearing tefilin. This is cited in Beit Yosef, which answers that Kol Bo relied on the view that the Sages indeed object to Michal. Olat Tamid (an early commentary on Shulḥan Arukh) 38:3 rejects Maharam’s view: if the prohibition on women wearing tefilin is based on cleanliness, why does Berakhot 20a state that they are exempt because it is a time-bound positive mitzva? Moreover, Michal wore tefilin and the Sages did not object. Therefore, Olat Tamid concludes: “We do not object to an old woman who we know is capable of guarding herself, and it is sort of case that they are discussing there [ in reference to Michal.” It is also said of several righteous women from early and later generations – including the wife of R. Ḥayim ibn Atar – that they wore tefilin.
The practical ruling is that a woman should not wear tefilin, and many authorities – including Rema, Kaf Ha-ḥayim, MB, and many others – state that objections should be raised against women who wish to wear tefilin. Nevertheless, a woman who wishes to wear tefilin has authorities to rely upon – Orḥot Ḥayim and Olat Tamid – and AHS also concludes that one should not object to one who is renowned as a righteous woman. Therefore, in practice, one should not object to this practice. However, a woman who wear tefilin should take care not to wear them while menstruating (though she may wear tefilin while counting her clean days) and should make sure to wear them in private, so that it is clear that she is wearing them for God’s sake and so that she does not advertise when she is menstruating.