Who is "the king in Yisrael" referring to?
Rashi #1 and Ramban #1: It refers to Hakadosh-Baruch-Hu, 1 whose sovereignty Yisrael accepted upon themselves and their children until the end of time, when the entire nation gathered together at Har Sinai. 2
Rashi #2 (in Bamidbar 10:2), 3 Ramban #2 and Targum Yonasan: It refers to Moshe Rabeinu 4 -(before whom they blew trumpets, like a king - Rashi).
Seforno: It refers to the G-d, who is king over those who study the Torah and who observe it.
Ramban: See Rosh Hashanah, 32b.
Ramban: As we saw in Pasuk 3, and that is what rendered them worthy of the forthcoming B'rachos. See also Devarim 5:24.
Refer to Bamidbar 10:2:1:1*.
See Na'ar Yonasan and Ramban DH 'Aval Yesh'.
Why does the Torah refer to Yisrael as "Yeshurun"?
Ramban: Because Matan Torah occurred when Yisrael were 'Yesharim' - straight, without sin. 1
Hadar Zekenim: Ya'akov is called 'Yeshurun', because the five humdred and seventy two years from Ya'akov until David ha'Melech became king 2 are equivalent to the Gematriya of "Yeshurun".
According to R. Bachye, 'Yeshurun' is an expression of 'seeing' (as in Bamidbar, 24:17), and the Torah refers to Yisrael by that name because they saw the Shechinah on Har Sinai.
How is that? Ya'akov lived 17 years in Egypt. Yisrael left 193 years later. David became king 436 later, and he reigned 40 years, and Shlomo subsequently began building the Beis ha'Mikdash in the fourth year of his reign, 480 years after leaving Egypt (Melachim 1 6:1)! Perhaps he counts from the death of Yosef, who is called "Toldos Ya'akov" (Bereishis 37:2); we find that as long as Yehoshua lived, it is as if his Rebbi Moshe lived (refer to 31:29:1:1). Yosef died 139 years before Yetzi'as Mitzrayim - 575 years before David. If we include the 'Beis' in bi'Yeshurun, the Gematriya is 574. Sometimes in Gematriya we add one for the word itself. Or, the calculation counted partial years like full years; really, there were only 574 years in between. If we take the Gematriya of "Yeshurun" without the 'Beis', it is like the years until Sha'ul became king (two years before David - PF).
Why does the Torah write that Hakadosh-Baruch-Hu is King specifically in Yisrael?
Rashi: What the Pasuk really means is that they (are the only ones who) always bear the yoke of His Sovereignty.
Why does the Torah discuss Torah separately - in the previous Pasuk and Malchus Shamayim separately - in the current Pasuk?
Ramban: The Torah first mentions Torah in general, 1 and then Malchus Shamayim 2 - because anyone who accepts Malchus Shamayim, he denies Avodah Zarah and acknowledges the whole Torah.
Ramban: Which Yisrael received from Moshe, and which they undertook to observe - whatever he commanded them in the name of 'the King', as the Torah wrote in Devarim 5:24.
Ramban: Which they accepted when Hashem proclaimed "Anochi".
What are the connotations of "be'His'asef Rashei Am... "?
Rashi #1: It means 'Whenever all the tribes of Yisrael gather together and are counted 1 they take upon themselves Malchus Shamayim' - which is why they are worthy of the blessing that Moshe is about to confer upon them.
Rashi #2 and Ramban (citing the Sifri): 'Hakadosh-Baruch-Hu is their King 'whenever the tribes of Yisrael gather together as one group and peace reigns among them'. 2
Seforno: It refers to Matan Torah, 'when the leaders of the tribes and their elders approached Moshe, 3 that is when Hashem became King over all of Yisrael - since that was when they all accepted His Sovereignty.
Kol Eliyahu 4 : The Pasuk refers to the four times that Yisrael accepted Hashem's authority over them. "Vay'hi bi'Yeshurun Melech" refers to Shiras ha'Yam when Yisrael accepted the yoke if His kingship; 5 - "Behis'asef Rashei Am", to accepting the yoke of Torah before Matan Torah 6
Rashi: As in Sh'mos, 30:12.
Rashi: But not when (they break-up into small groups - Ramban) there is Machlokes among them. See Ramban DH 've'Chein Shaninu'.
Seforno: See Devarim 5:20.
Divrei Eliyahu gives a similar explanation, only he says that we crowned Hashem king in the Shirah, and accepted the yoke of His kingship three times.
When they proclaimed "Hashem Yimloch le'Olam va'Ed" - Sh'mos 15:18.
"Vayikra le'Ziknei ha'Am
