Why did Hashem insert the word "ve'Atah" here?
Mechilta: To teach Moshe to convey Shabbos to Yisrael directly, not through a Shali'ach and not through an interpreter. 1
Oznayim la'Torah: Hashem appointed three good leaders for Yisrael (Ta'anis, 9a - Moshe, Aharon and Miriam - who sanctified Yisrael , thereby enabling the Shechinah to dwell in Yisrael. Miriam's grandson Betzal'el made the Bigdei Kehunah for Aharon, who was chosen to perform the Avodah in the Beis-Hamikdash for all time (Kedushas ha'Makom). Whereas Moshe sanctified Yisrael with Shabbos (Kedushas ha'Zeman). Hence we find that Moshe was deeply involved with Shabbos already at Marah, where he pointed out to Yisrael via the Manna the Kedushah of Shabbos, when he said to the people "See, that Hashem has given you the Shabbos!". And here , where he informed them about the reward of keeping the Shabbos, the severe punishment for breaking it. And the fact that it is a sign between Hashem and them. 2
To avoid mistakes and misunderstandings regarding Shabbos, which carries the death-penalty and which is the basis of our religion. See also Torah Temimah, note 12.
Why does the Torah insert the Parshah of Shabbos after the Meleches ha'Mishkan?
Rashi, Ramban, Rashbam and Seforno: Hashem is informing Moshe that, in spite of the importance of building the Mishkan, it does not override Shabbos. 1
Da'as Zekenim, Hadar Zekenimn and Rosh: To teach that all the major Melachos that were performed in the Mishkan form the Avos Melachos on Shabbos.
According to Rashi, we learn it from the word "Ach" (Refer to 31:13:2:1); according to other commentaries, from the fact that the Torah inserts Shabbos immediately after the Mishkan. Refer to 31:13:1:3. The Ramban adds that the Sifra learns that Shabbos does not override building the Mishkan from the Pasuk in Kedoshim Vayikra, 19:30 - "Es Shabsosai Tishmoru u'Mikdashi Tira'u, Ani Hashem". Based on the current Pesukim, the Seforno adds a number of reasons as to why the construction as the Mishkan does not override Shabbos: 1. Refer to 31:13:4:2. 2. Because Shabbos incorporates an Asei (Ki Kodesh Hi lachem") and a Lo Sa'aseh ("Mechalelehah Mos Yumas"). 3. Because desecrating it is an exceptionally severe sin inasmuch as the soul of the sinner is cut off from the world to come, and 4. Refer to 31:14:2:1.
Why does the Torah insert the word "Ach"?
Rashi: It comes to preclude building the Mishkan on Shabbos. 1
Ramban #1: It comes to preclude B'ris Milah and Piku'ach Nefesh, 2 both of which override Shabbos. 3
Ramban #2 (in Emor Vayikra, 23:27): It means 'in truth', as if to say that Hashem may have commanded the building of the Mishkan, but Shabbos must always be observed. 4
Ba'al ha'Turim: It comes to preclude a. Piku'ach Nefesh, b. the Korbanos of Shabbos 5 and c. when fighting the enemy - "ad Ridtah" (Shoftim Devarim, 20:20) 'Afilu be'Shabbos' from the Isur of Melachah on Shabbos.
Why does the building of the Mishkan not override that of Shabbos inthe same way as the Avodah in the Mishkan does?
Oznayim la'Torah: Because the Kedushah of time - which can never negated 1 - is greater than that of location, which is subject to destruction (like we find by the Churban Beis-Hamikdash)..
As the Torah indicates here when it inserts the word "le'Doroseichem".
Why does the Torah write "Shabsosai" (plural)
Ramban #1, Targum Onkelos and Targum Yonasan: It refers to the many Shabbasos during the year.
Ramban #2: It hints at the two aspects of Shabbos '"Zachor" (the Mitzvas Asei) and "Shamor" (Mitzvas Lo Sa'aseh). 1
Shabbos, 69b: The Torah writes here "es Shabsosai Tishmoru" - in the plural - to teach us that a person who knows about Shabbos and who forgot and performed many Melachos on many Shabbasos, is Chayav a Chatas for each Shabbos; 2 whereas in Pasuk 16 it writes "Veshamryu B'nei Yisrael es ha'Shabbos" - in the singular - to teach us that if he forgot the concept of Shabbos and performed many Melachos on many Shabbasos, he is Chayav only one Chatas.
What are the implications of the word "Es Shabsosai Tishmoru"?
Mechilta: It hints at the obligaton to keep the Shevusim (the prohibitions which the Chachmim instituted). 1
Oznayim la'Torah: With reference to the fact that Piku'ach Nefesh overrides Shabbos (Refer to 31:13:1:3), it hints at the reason stated in the Gemara there - 'It is worthwhile desecrating one Shabbos, so that Hillel will go on to keep many Shabbasos!'
See Torah Temimah, note 16.
What is the significance of the phrase "Ki Os Hi"?
Rashi and Rashbam: The fact that Hashem designated for Yisrael His personal day of rest as their day of rest highlights the closeness of their relationship, and demonstrates to the nations of the world that Hashem sanctifies Yisrael. 1
Seforno: In the event that Yisrael break the sign, there is no justification to construct the Mishkan. 2
Rashi (in Menachos, 17b): It teaches us that Shabbos is called an Os and that there is therefore no need to wear Tefilin on Shabbos. 3
As the Pasuk goes on to state (Rashi).
This is one reason as to why the Mishkan does not override Shabbos. Refer also to 31:14:1:2 & 31:15:1:1*.
Or on Yom'Tov, which is also calles 'Shabbos' - See Torah Temimah, note 17.
What are the connotations of the word "Lada'as ki Ani Hashem Mekadishchem"?
Rashi: It means so that the nations of the world should know via the Shabbos that Hashem sanctifies us. 1
Mechilta: It implies that one is not obligated to stop a 'Chashu' (Cheresh, Shotah ve'Katan) - who do not have Da'as - from performing Melachos on Shabbos. 2
Shabbos, 10b: It means that Moshe should let Yisrael know about the precious gift (Shabbos) that is lying in His treasury 3 - that He intends to give to them. 4
See Torah Temimah, note 18.
Oznayim la'Torah: Bearing in mind the Gemara in B'rachos, 33b 'The only thing that Hashem stores in His treasury is Yir'as Shamayim;, it is clear that Shabbos is a Segulah for Yir'as Shamayim. That being the case, when we keep Shabbos, Shabbos sanctifies us with Yir'as Shamayim (refer to 31:14:0.2:1) - And that is the reward of Shabbos, about which Moshe informed them immediately when he said "Ki Ani Hashem Mekadishchem". See Oznayim la'Torah, who elaborates.
Shabbos (Ibid.): From here the Chachamim said that someone who gives his friend a gift should inform him, though not if it is bound to become revealed anyway. See also Torah Temimah, note 19.
What is the significance of the phrase "ki Ani Hashem Mekadishchem"?