אורח חיים ס״אOrach Chayim 61

Se’if 1א׳

יִקְרָא קְרִיאַת שְׁמַע בְּכַוָּנָה, בְּאֵימָה וּבְיִרְאָה, בְּרֶתֶת וָזִיעַ.

Laws of how much one needs to be precise and have intention during the Recitation of the Sh'ma; contain 26 se-ifim One should recite the Sh'ma with intention, awe, fear, shaking and trembling.

Se’if 2ב׳

אֲשֶׁר אָנֹכִי מְצַוְּךָ הַיּוֹם, הַיְנוּ לוֹמַר בְּכָל יוֹם יִהְיוּ בְּעֵינֶיךָ כַּחֲדָשִׁים, וְלֹא כְּמִי שֶׁכְּבָר שָׁמַע אוֹתוֹ הַרְבֵּה פְּעָמִים, שֶׁאֵינוֹ חָבִיב אֶצְלוֹ.

[The verse states:] "Which I have commanded you today," (Deuteronomy 6:6) - which teaches that every day it should appear in your eyes as if it was new, and not like someone who already heard it many times and is [therefore] not precious to him.

Se’if 3ג׳

בִּקְרִיאַת שְׁמַע יֵשׁ רמ "ה תֵּבוֹת, וּכְדֵי לְהַשְׁלִים רמ "ח כְּנֶגֶד אֵיבָרָיו שֶׁל אָדָם, מְסַיֵּם שְׁלִיחַ צִבּוּר ה' אֱלֹהֵיכֶם אֱמֶת, וְחוֹזֵר וְאוֹמֵר בְּקוֹל רָם ה' אֱלֹהֵיכֶם אֱמֶת: הַגָּה: וּבָזֶה כָּל אָדָם יוֹצֵא, הוֹאִיל וְשׁוֹמְעִין מִפִּיו שֶׁל הַשְּׁלִיחַ צִבּוּר ג' תֵּבוֹת אֵלּוּ (בֵּית יוֹסֵף בְּשֵׁם א"ח) וְאִם הַיָּחִיד רוֹצֶה גַּם כֵּן לְאָמְרָם עִם הַשְּׁלִיחַ צִבּוּר, אֵין אִסּוּר בַּדָּבָר (דִּבְרֵי עַצְמוֹ) וְאִם הוּא קוֹרֵא בְּיָחִיד, יְכַוֵּן בְּט"ו וָוִי"ן שֶׁבֶּאֱמֶת וְיַצִּיב שֶׁעוֹלִים צ', וְהֵם כְּנֶגֶד ג' שְׁמוֹת הַהֲוָיָ"ה, שֶׁכָּל שֵׁם עוֹלָה כ"ו וְד' אוֹתִיּוֹתָיו הֵם ל': הַגָּה: וְיֵשׁ עוֹד טַעַם אַחֵר בַּדָּבָר דְּט"ו וָוִי"ן עוֹלִין צ', וְהַקְּרִיאָה נֶחְשֶׁבֶת א', הֲרֵי צ"א כְּמִנְיַן הַשֵּׁם בִּקְרִיאָתוֹ וּבִכְתִיבָתוֹ, וְהָוֵי כְּאִלּוּ אָמַר ד' אֲדֹנָ"י אֱמֶת (מַהֲרִי"ק שֹׁרֶשׁ מ"ב וְאָגוּר) וְיֵשׁ שֶׁכָּתְבוּ דְּכָל הַקּוֹרֵא קְרִיאַת שְׁמַע בְּיָחִיד, יֹאמַר אֵל מֶלֶךְ נֶאֱמָן שְׁמַע וְגו', כִּי ג' תֵּבוֹת אֵלּוּ מַשְׁלִימִים הַמִּנְיָן שֶׁל רמ"ח, וְהוּא בִּמְקוֹם אָמֵן שֶׁיֵּשׁ לַעֲנוֹת אַחַר בָּרוּךְ הַבּוֹחֵר בְּעַמּוֹ יִשְׂרָאֵל בְּאַהֲבָה, וְכֵן נוֹהֲגִין. וְנִרְאֶה לִי מִכָּל מָקוֹם כְּשֶׁקּוֹרֵא עִם הַצִּבּוּר, לֹא יֹאמַר אֵל מֶלֶךְ נֶאֱמָן, רַק יֹאמַר אָמֵן אַחַר הַשְּׁלִיחַ צִבּוּר כְּשֶׁמְּסַיֵּם הַבְּרָכָה, וְכֵן נוֹהֲגִין, וְנָכוֹן הוּא.

In the recitation of Shema there are 245 words, and in order to complete 248, which corresponds to the limbs of the human body, the prayer leader concludes "Hashem your God is true" and repeats and says aloud "Hashem your God is true." Rema: And through this every person fulfills their obligation, since they hear these three words from the mouth of the prayer leader (Beit Yosef in the name of Orchot Chaim). And if the individual wants to say them along with the prayer leader, it is not forbidden (his own words). And if he's reading alone, have in mind regarding the fifteen vavs in "Emet V'yatziv" which equal 90, and they correspond to three divine Names, where each Name equals 26 and its four letters are 30. Rema: And there's another reason for doing so, since the fifteen vavs add up to 90, and the reading counts as one, this is then 91, which is the value of the God's name as it is pronounced and written, and it's as if he said "Hashem Adonai emet" (Maharik Root 42 and Agur). And there are those who wrote that anyone who recites Shema alone should say "El melech ne'eman Shema, etc.," because these three words complete the count of 248, and this comes in place of the Amen that one is required to answer after "Blessed is He who chooses His people Israel with love," and so is the custom. And it seems to me nevertheless that when reciting with the congregation, one should not say "El melech ne'eman" but rather should say "Amen" after the prayer leader concludes the blessing, and this is our custom and it is correct.