What is the significance of being one, without a son or brother?
Rav Sadya Gaon: Even though he is alone, there is no limit [to his toil].
Rashi: He does things alone - if he is a Chacham, he does not acquire a Talmid, who is like a son, nor a colleague, who is like a brother. If he is a bachelor, he does not marry a wife, who would be like a brother to him and bear a son to him. If he is a merchant, he does not acquire partners, and goes on the road alone.
Ibn Ezra: "Sheni" is a friend, servant or wife, who is "Ezer k'Negedo" (Bereishis 2:20). This is the best Perush (a wife). Also refer to 4:8:4:2 and the note there.
Rashbam, Metzudas David: He toils ardently, and does not want someone else to help him, to take a share of the merchandise and toil.
Ri Kara, Rid: One cannot say that he toils to finance others.
R. Avigdor citing Koheles Rabah #1: This is Hashem - "Shma Yisrael Hashem Elokeinu Hashem Echad" (Devarim 6:4). Obviously He has no son or brother! Rather, because He endeared Yisrael, and called them 1 "Banim Atem la'Shem Elokeichem" (Devarim 14:1), and "Lema'an Achai v'Re'ai" (Tehilim 122:8)
R. Avigdor citing Koheles Rabah #2: "Echad v'Ein Sheni" hints to the Yetzer ha'Ra. "Ra mi'Ne'urav" (Bereishis 8:21) - it enters a baby from when it is Nin'ar (moves) to leave the womb. The Yetzer Tov does not enter until 13 years and one day 2 .
Seforno: "Echad v'Ein Sheni" - there is no one to receive Chesed from him, that it will be considered Tzedakah.
Therefore, the verse needs to say that really, He has no son or brother. (PF)
R. Avigdor: Therefore, a boy is not proper for Mitzvos until he is 13, and Esav was recognized for his evil deeds only after 13 - "va'Yigdelu ha'Ne'arim va'Yhi Esav" (Bereishis 25:27). Because the Yetzer ha'Ra is in man from his youth, it is called "Melech". It is called "Melech Zaken u'Chesil" (below, 13), for it is 13 years older than the Yetzer Tov.
What do we learn from "v'Ein Ketz
Refer to 4:8:1:1.
Rashi: He exerts greatly to learn the text 1 . If he is a merchant, he toils with merchandise 2 .
Ibn Ezra: He has wealth and there is no limit.
Ri Kara: He works day and night to amass wealth.
R. Avigdor citing Koheles Rabah: There is no limit to what Hashem did in the six days of creation.
Seforno: He toils to attain excesses, without Ketz (limit, or purpose).
Metzudas David: He works constantly, without resting.
What do we learn from "Gam Eino Lo Sisba Osher"?
Ibn Ezra: His Nefesh is not satiated, and does not rest from toil.
Ri Kara: Even though he amasses great wealth, he is not satiated. He always toils for money. Metzudas David - he always wants more.
R. Avigdor: "Eino" is written Chaser (without 1 a Yud), to hint that the Yetzer ha'Ra makes him sin, and transgress Aseres ha'Dibros.
Seforno: He is not happy with his wealth.
Ayin always has a silent Yud before the Nun. Our texts have an extra silent Yud before the Nun! Presumably, the text of R. Avigdor should say so; there is a printing mistake. (PF)
What is the question "ul'Mi Ani Amel"?
Rashi: Since I do not establish Talmidim, or marry and father children, for whom do I toil 1 ?
Ibn Ezra: Why does he not think, why do I deprive my Nefesh from all pleasure? There is no one to inherit me 2 , that I will rejoice leaving my son or brother in good [financial status]!
Ri Kara: He should put to his heart, I toil constantly, and tomorrow I will die, and others will consume [my toil]!
Seforno: Since I toil for more than I need - for whom is it?
Metzudas David: He does not think, for whom do I toil, and deprive my Nefesh of good, serenity and rest? I have no son or brother to inherit me. I will leave my wealth to others!
Rashi did not explain according to the Perush that he is a merchant. Perhaps if he had a partner, he toils greatly, for also his partner does so for him. (PF)
If he not is a convert, he always has an heir! However, one does not feel so close to other heirs (e.g. cousins; he does not expect to die before his father and bequeath to his father) that he would rejoice to bequeath to them. (PF)
From what Tov does he deprive his Nefesh?
Seforno: It will not attain any eternal perfection.
Why does it say "Gam Zeh Hevel"?
Ibn Ezra: Also the first Kesil (5-6; he who does not work, and starves) is Hevel, like the latter. A Chacham [works for his needs -] "Reish va'Osher Al Titen Li" (Mishlei 30:8).
Metzudas David: Even though idleness is lowly, increasing toil is Hevel and an evil Inyan.
What is "Inyan Ra"?
Seforno: He toils to attain excesses, without Ketz (limit), and deprives his Nefesh from good.
