Why should Yaakov accompany Leah after three sons?
Rashi: She knew that Yaakov will have 12 sons from four wives, so she gave birth to her proper share.
Riva citing R"M mi'Kutzi: I can handle only two. Now he will need to help me. 1
Tosfos ha'Shalem (3, citing R. Efrayim): I can handle one, and my Shifchah can handle one. Yaakov will need to engage with the third. 2
Tosfos ha'Shalem (5): Yaakov must teach the oldest Torah and Yir'as Shamayim, and I will deal with the younger.
Ohr ha'Chayim #1: One could attribute the first two sons to removing hatred, and causing Yaakov to love her. Her third son must be because she is his Zivug; Hashem caused that he marry her.
Ohr ha'Chayim #2: He will accompany her after leaving this world, for she is his Zivug. Three sons make a Chazakah! Also, she knew through Ru'ach ha'Kodesh that Yaakov will have 12 sons through four wives (so she has a proper share; surely she is a Zivug of him).
Malbim: The hatred has abated, so this time he should accompany me.
Regarding the other sons, the mother gave the name. Why does it say here "He called him"?
Rashi: Hashem called him Levi, because he accompanied him with 24 gifts of Kehunah.
Rashbam: Yaakov called him Levi. 1
Why does it say "Al Ken" regarding calling the names of Levi, Yehudah and Dan?
Ha'amek Davar: For these, the name reflects the destiny of the [Shevet of the] child. 3 E.g. Levi is based on Leviyah; he will be more connected to Hashem than the other Shevatim.
Yehudah was the biggest Shevet, and Dan was second, even though Dan had only one son!
Ha'amek Davar (to 29:35, 30:6): Regarding Yehudah, all Yodu (will admit) to his strength and Chochmah. People from Dan will want Din (judgment - Pesachim 4a).
QUESTIONS ON RASHI
Rashi writes: "For the Imahos were prophets." Yet, the Gemara (Megilah 14a) does not list Rachel and Leah among the prophetesses?
Gur Aryeh: The Gemara only counts the prophets (whether male or female), the content of whose prophecy is recorded by Tanach. 1 That of Rachel and Leah is only alluded to.
Refer to 30:20:2:1**.
Gur Aryeh: For instance, Sarah is counted, for (she was called Yiskah due to her prophecy, and), Hashem later affirmed her specific prophecy regarding Yitzchak and Yishmael, saying, "all that Sarah says, heed her voice" (21:12).
Rashi writes: "Hashem sent the angel Gavriel...." We find that Yaakov was named by Hashem Himself (Rashi to 25:26); why was Levi named though an angel?
Gur Aryeh: Yaakov would be one of the Avos, the Merkavah (Chariot) of Hashem. 1 Yaakov did not need an angel; he was named by Hashem himself - whereas Levi was not at that level of the Avos.
Rashi writes: "'Al Ken' (as such) - Anyone about whom it is said 'Al Ken' had a large population (except for Levi)." Why is this so?
Gur Aryeh #1: 'Ken' connotes an amount or a specification - e.g. 'Yehi Ken - Let it be just so.' "Al Ken" means above and beyond any specified amount.
Gur Aryeh #2: "Al Ken Kara" gives a reason for the name in question, making his name an intrinsic part of himself, giving him identity. A large population is necessary for maintaining an independent identity, for a small tribe is liable to be subsumed under another tribe's name.
Gur Aryeh #3: "Al Ken" attaches the reason to the name. A reason is an intellectual (i.e. non-physical) entity, on a higher plane, and that is the source of the increase.
Rashi writes that Levi did not have many people, for the Aron would diminish their number. But the census in Bamidbar (Ch. 3) was a mere month after the inauguration of the Mishkan, and before they carried the Aron on their travels - and even then, the Tribe of Levi was small in number?
Riva, citing R"M of Kutzi; Ramban (to Bamidbar 3:14); Gur Aryeh: The rest of Am Yisrael had increased dramatically in number, in accordance with their degree of affliction at the hands of the Egyptians, "As much as they made them suffer, so would they increase" (Shemos 1:12). The tribe of Levi, however, was never enslaved (see Rashi to Shemos 5:4), and so it did not multiply miraculously either. 1
Divrei David: 'Al Ken' represents a significant, befitting achievement. Other Shevatim achieved their sum total Kedushah through their large numbers. The Leviyim were qualitatively greater in Kedushah, as shown by their service in the Mishkan and with the Aron, 2 and could achieve the same with fewer numbers. 3
Gur Aryeh: This was the cause of their small number at the time of the Exodus. Rashi is explaining why they did not increase after the Exodus. Ramban (to Bamidbar 3:14) - Perhaps it also owed back to Yaakov's displeasure with Shim'on and Levi's deeds.
Only Bnei Kehas carried the Aron. Kehas was bigger than the other families of Levi (Gershon and Merari - see Bamidbar 3:22,28,34)! Perhaps carrying all parts of the Mishkan required great Kedushah; the Aron was specified, for it also killed. (PF)
Rashi writes: "... Other than Levi; for the Aron would diminish their number." Did the Leviyim disgrace the honor of the Aron?!
Gur Aryeh: At times, they may have been unwittingly lax (Shogeg) in guarding its sanctity. 1
For example, the Navi teaches that Uza died for unwitting disrespect towards the Aron (Shmuel II 6:6-7). (I have not found a source as to whether Uza was a Levi. On the other hand, Oved Edom ha'Giti was a Levi of the family of Kehas (Divrei ha'Yamim I 26), who was incredibly blessed in number due to his care and respect for the Aron while it was in his home (Shmuel II 6:11; see Berachos 63b).) (CS)