Why does the Torah juxtapose the Parshah of Nazir next to that of Sotah?
Rashi: Because whoever sees a Sotah in her ruin 1 should make a Neder of Nezirus, to abstain from drinking wine.
How they abuse her by uncovering her hair and part of her body (Sifsei Chachamim).
What is the meaning of "Ish ki Yafli ... "?
Rashi: A man who separates from wine.
Seforno: A man who separates from the vain pleasures of this world. 1
Rashi (in Chagigah, 10a, citing Targum Onkelos): A man who expresses (verbalizes) a Neder of Nezirus.
Seforno: Which the words "Lindor Neder Nazir" imply.
What are the implications of the words "Lehazir la'Hashem"?
Seforno: It implies that the objective of Nezirus is to dispel every vestige of materialism 1 and to become 'Kulo la'Hashem'.
Seforno (on Pasuk 3): Not by fasting, which impedes one's Avodas Hashem - as Chazal have said, or by self-flagellation, but by desisting from wine, which diminishes one's desires and subjugates one's Yeitzer-ha'Ra, without infringing one's strength to serve Hashem.
QUESTIONS ON RASHI
Rashi writes that whoever sees a Sotah in her ruin should accept Nezirus. A Nazir brings a Korban, to atone for paining himself [through abstaining] from wine!
Riva (1) #1: "Yazir" does not mean to accept Nezirus, rather, to limit wine, and not get drunk, which leads to filth (Zenus).
Riva (1) #2: [Only] a Nazir Tamei is called a sinner, like it says in Nazir 3a, because the first days are canceled, and he is prone to transgress his Nezirus (he never expected to refrain so long), but a Nazir Tahor who intends l'Shem Shamayim is not a sinner.
Riva (1) #3: Granted, it is a Mitzvah [for one who sees a Sotah] to become a Nazir, but there is a small Aveirah. We find that it is a Mitzvah to fast on Shabbos due to a bad dream, even though he must fast the next day to atone for fasting on Shabbos, and similarly here.
Rashi writes that whoever sees a Sotah in her ruin should accept Nezirus. This applies to women, but not to men!
Moshav Zekeinim, citing Ri: The water kills also the Bo'el. He should be accept Nezirus, for wine gladdens the heart and brings to physical lusts. Also growing hair is the opposite of bachelors who curl their hair for beauty and pride. 1 Growing hair leads a person to worry, therefore he is Kadosh. And he must guard from Tum'ah, for he is a Kohen who serves his G-d.
I.e. their hair is not long, but they curl it. (PF)