(א) הָיָה קוֹרֵא בַתּוֹרָה, וְהִגִּיעַ זְמַן הַמִּקְרָא, אִם כִּוֵּן לִבּוֹ, יָצָא. וְאִם לָאו, לֹא יָצָא.
בַּפְּרָקִים שׁוֹאֵל מִפְּנֵי הַכָּבוֹד וּמֵשִׁיב, וּבָאֶמְצַע שׁוֹאֵל מִפְּנֵי הַיִּרְאָה וּמֵשִׁיב, דִּבְרֵי רַבִּי מֵאִיר.
רַבִּי יְהוּדָה אוֹמֵר, בָּאֶמְצַע שׁוֹאֵל מִפְּנֵי הַיִּרְאָה, וּמֵשִׁיב מִפְּנֵי הַכָּבוֹד, בַּפְּרָקִים שׁוֹאֵל מִפְּנֵי הַכָּבוֹד, וּמֵשִׁיב שָׁלוֹם לְכָל אָדָם:
If one was reading in the Torah out loud, and the time for reciting [the Shema] arrives - if one directs one's heart, one goes out [from one's obligation], but if not, one does not go out.
In the breaks [between sections] one may give a greeting out of respect, and return a greeting. In the middle [of a section] one may give a greeting out of fear and return it. These are the words of Rabbi Meir.
Rabbi Judah says: in the middle [of a section] one may give a greeting out of fear and return it out of respect. In the breaks [between sections], one may give a greeting out of respect and return a greeting to anyone.
גְּמָ׳ שְׁמַע מִינַּהּ מִצְוֹת צְרִיכוֹת כַּוָּונָה.
מַאי ״אִם כִּוֵּון לִבּוֹ״ — לִקְרוֹת. לִקְרוֹת?! וְהָא קָא קָרֵי! בְּקוֹרֵא לְהַגִּיהַּ.
GEMARA: You learn from this that mitzvot require intention.
What does "If one directs one's heart" mean? It means, direct one's heart to reciting.
But they are reciting!!
This applies to someone who is reading through to check for mistakes.
(ב) אֵלּוּ הֵן בֵּין הַפְּרָקִים, בֵּין בְּרָכָה רִאשׁוֹנָה לִשְׁנִיָּה, בֵּין שְׁנִיָּה לִשְׁמַע, וּבֵין שְׁמַע לִוְהָיָה אִם שָׁמֹעַ, בֵּין וְהָיָה אִם שָׁמֹעַ לְוַיֹּאמֶר, בֵּין וַיֹּאמֶר לֶאֱמֶת וְיַצִּיב. רַבִּי יְהוּדָה אוֹמֵר, בֵּין וַיֹּאמֶר לֶאֱמֶת וְיַצִּיב לֹא יַפְסִיק. אָמַר רַבִּי יְהוֹשֻׁעַ בֶּן קָרְחָה, לָמָּה קָדְמָה שְׁמַע לִוְהָיָה אִם שָׁמֹעַ, אֶלָּא כְדֵי שֶׁיְּקַבֵּל עָלָיו עֹל מַלְכוּת שָׁמַיִם תְּחִלָּה, וְאַחַר כָּךְ יְקַבֵּל עָלָיו עֹל מִצְוֹת. וְהָיָה אִם שָׁמֹעַ לְוַיֹּאמֶר, שֶׁוְהָיָה אִם שָׁמֹעַ נוֹהֵג בַּיּוֹם וּבַלַּיְלָה, וַיֹּאמֶר אֵינוֹ נוֹהֵג אֶלָּא בַּיּוֹם:
These are the breaks between the sections: between the first blessing and the second, between the second and Shema, between Shema and 'And it shall come to pass if you listen' between 'And it shall come to pass if you listen' and 'And the Lord said' and between 'And the Lord said' and 'Emet veYatziv' (true and firm). Rabbi Judah says: between 'And the Lord said' and 'Emet veYatziv' one should not interrupt. Rabbi Yehoshua ben Korhah said: Why was the section of Shema placed before that of 'And it shall come to pass if you listen'? So that one should first accept upon oneself the yoke of the Kingdom of Heaven and then take upon oneself the yoke of the commandments. Why does the section of 'And it shall come to pass if you listen' come before that of 'And the Lord said'? Because 'And it shall come to pass if you listen' is customary during both day and night, whereas 'And the Lord said' is customary only during the day.