Jewish tradition draws from a number of texts. This source sheet explains many of them, using the recitation of the Shema as an example of how each source works and how Jewish law evolves through the sources.
The Masorites added the trope and the vowels in the Land of Israel in the 800s; because trope also function as punctuation, this defined where the verses ended as well. The Archbishop of Canterbury, Stephen Langton, added chapters around 1200; this explains why the 7th day of Creation is in the same aliyah as the other 6 days (a Jewish division), but it is in Chapter 2 of Genesis instead of Chapter 1 (a Christian division). Jews nonetheless embraced chapters, even if they didn’t always line up with Jewish divisions. Christians didn’t get around to putting verse numbers in their translations until the Geneva Bible of 1551, which drew on the Jewish division of verses.
ה' אלהינו ה' אחד. ה' שֶׁהוּא אֱלֹהֵינוּ עַתָּה, וְלֹא אֱלֹהֵי הָאֻמּוֹת, הוּא עָתִיד לִהְיוֹת ה' אֶחָד, שֶׁנֶּאֱמַר (צפ' ח') כִּי אָז אֶהְפֹּךְ אֶל עַמִּים שָׂפָה בְרוּרָה לִקְרֹא כֻלָּם בְּשֵׁם ה', וְנֶאֱמַר (זכריה י"ד) בַּיּוֹם הַהוּא יִהְיֶה ה' אֶחָד וּשְׁמוֹ אֶחָד (ע' ספרי):
ה׳ אלהינו ה' אחד means, The Lord who is now our God and not the God of the other peoples of the world, G-d will at some future time be the One (sole) ה׳, as it is said, (Zephaniah 3:9) “For then I will turn to the peoples a pure language that they may all call upon the name of the Lord", and it is further said, (Zechariah 14:9) “In that day shall the Lord be One (אחד) and His name One" (cf. Sifrei Devarim 31:10).
(א) מֵאֵימָתַי קוֹרִין אֶת שְׁמַע בְּעַרְבִית. מִשָּׁעָה שֶׁהַכֹּהֲנִים נִכְנָסִים לֶאֱכֹל בִּתְרוּמָתָן, עַד סוֹף הָאַשְׁמוּרָה הָרִאשׁוֹנָה, דִּבְרֵי רַבִּי אֱלִיעֶזֶר. וַחֲכָמִים אוֹמְרִים, עַד חֲצוֹת. רַבָּן גַּמְלִיאֵל אוֹמֵר, עַד שֶׁיַּעֲלֶה עַמּוּד הַשָּׁחַר. מַעֲשֶׂה שֶׁבָּאוּ בָנָיו מִבֵּית הַמִּשְׁתֶּה, אָמְרוּ לוֹ, לֹא קָרִינוּ אֶת שְׁמַע. אָמַר לָהֶם, אִם לֹא עָלָה עַמּוּד הַשַּׁחַר, חַיָּבִין אַתֶּם לִקְרוֹת. וְלֹא זוֹ בִּלְבַד, אֶלָּא כָּל מַה שֶּׁאָמְרוּ חֲכָמִים עַד חֲצוֹת, מִצְוָתָן עַד שֶׁיַּעֲלֶה עַמּוּד הַשָּׁחַר. הֶקְטֵר חֲלָבִים וְאֵבָרִים, מִצְוָתָן עַד שֶׁיַּעֲלֶה עַמּוּד הַשָּׁחַר. וְכָל הַנֶּאֱכָלִים לְיוֹם אֶחָד, מִצְוָתָן עַד שֶׁיַּעֲלֶה עַמּוּד הַשָּׁחַר. אִם כֵּן, לָמָּה אָמְרוּ חֲכָמִים עַד חֲצוֹת, כְּדֵי לְהַרְחִיק אֶת הָאָדָם מִן הָעֲבֵרָה:
(1) From what time may one recite the Shema in the evening? From the time that the priests enter [their houses] in order to eat their terumah until the end of the first watch, the words of Rabbi Eliezer. The sages say: until midnight. Rabban Gamaliel says: until dawn. Once it happened that his sons came home [late] from a wedding feast and they said to him: we have not yet recited the [evening] Shema. He said to them: if it is not yet dawn you are still obligated to recite. And not in respect to this alone did they so decide, but wherever the sages say “until midnight,” the mitzvah may be performed until dawn. The burning of the fat and the pieces may be performed till dawn. Similarly, all [the offerings] that are to be eaten within one day may be eaten till dawn. Why then did the sages say “until midnight”? In order to keep a man far from transgression.
(א) משֶׁה קִבֵּל תּוֹרָה מִסִּינַי, וּמְסָרָהּ לִיהוֹשֻׁעַ, וִיהוֹשֻׁעַ לִזְקֵנִים, וּזְקֵנִים לִנְבִיאִים, וּנְבִיאִים מְסָרוּהָ לְאַנְשֵׁי כְנֶסֶת הַגְּדוֹלָה. הֵם אָמְרוּ שְׁלשָׁה דְבָרִים, הֱווּ מְתוּנִים בַּדִּין, וְהַעֲמִידוּ תַלְמִידִים הַרְבֵּה, וַעֲשׂוּ סְיָג לַתּוֹרָה:
(1) Moses received the Torah at Sinai and transmitted it to Joshua, Joshua to the elders, and the elders to the prophets, and the prophets to the Men of the Great Assembly. They said three things: Be patient in [the administration of] justice, raise many disciples and make a fence round the Torah.
Another idea: "Listen, O Israel-" from where did Israel merit the [commandment of the] reading of Shema? From the time that Jacob spread out to die, he called to all the tribes and said to them: "Maybe once I pass away, you will bow to another power?" From where [can we learn this]? For so it is written: "Gather and listen, sons of Jacob, [and listen to your father Israel] (Genesis 49)." What is 'and listen to your father Israel (Heb. V'shimu El Yisrael Avichem)'? He said to them: The G-d of Israel is your father (an alternate meaning of 'El Yisrael Avichem')." They said to him: "Listen O Israel, Hashem is our G-d, Hashem is one." And he said in a whisper: "Blessed be the glorious name of His Kingship (ie. G-d) forever." Rabbi Levi said: "And what do Israel say today? 'Listen, our forefather Israel, the same thing that you commanded us still abides among us, Hashem is our G-d, Hashem is one.'"
From what time do we read the shema at night? From the time that the Kohanim (priests) enter to eat their Trumah (holy food). --- Kohanim that became defiled, and then immersed (in the mikvah), and the sun has set [reseting their purity], then they are allowed to eat Trumah.
Orach Chayim - the laws about Jewish time (prayer time and holidays)
Yoreh De’ah - the laws about Jewish living (kashrut, conversion, mourning, Israel)
Even Ha’ezer - the laws about getting married and divorced
Choshen Mishpat - the laws about business, money, and courts
58:5. If for a good reason one did not read the evening Shema by dawn, since (20) the sun has not yet risen one can read the Shema and fulfill the evening Shema. And if he is in a rush because he is going to a place of wild animals and/or robbers, (21) he should still not read Shema (22) a second time in order to read the day’s Shema, because since he declared it to be night [by reading the evening Shema] he cannot go back (23) and make it day.
MB 20: the sun – And some people are sleeping at that time, therefore at a pressing time it is considered in the time frame of “and when you lie down” but normally, even after the fact, this is not sufficient to fulfill the commandment.
MB 21: he should not read – there are those who disagree, and see the Eliya Raba and the Gr”a.
MB 22: a second time – even after the time where he can recognize his friend at a distance of 4 amot [until sunrise].
MB 23: and make it day – rather he should wait, perhaps he will be able to say it at the proper time.