(א) וַיְדַבֵּ֥ר יְהֹוָ֖ה אֶל־מֹשֶׁ֥ה לֵּאמֹֽר׃ (ב) דַּבֵּר֙ אֶל־בְּנֵ֣י יִשְׂרָאֵ֔ל וְאָמַרְתָּ֖ אֲלֵהֶ֑ם אִ֣ישׁ אֽוֹ־אִשָּׁ֗ה כִּ֤י יַפְלִא֙ לִנְדֹּר֙ נֶ֣דֶר נָזִ֔יר לְהַזִּ֖יר לַֽיהֹוָֽה׃ (ג) מִיַּ֤יִן וְשֵׁכָר֙ יַזִּ֔יר חֹ֥מֶץ יַ֛יִן וְחֹ֥מֶץ שֵׁכָ֖ר לֹ֣א יִשְׁתֶּ֑ה וְכׇל־מִשְׁרַ֤ת עֲנָבִים֙ לֹ֣א יִשְׁתֶּ֔ה וַעֲנָבִ֛ים לַחִ֥ים וִיבֵשִׁ֖ים לֹ֥א יֹאכֵֽל׃ (ד) כֹּ֖ל יְמֵ֣י נִזְר֑וֹ מִכֹּל֩ אֲשֶׁ֨ר יֵעָשֶׂ֜ה מִגֶּ֣פֶן הַיַּ֗יִן מֵחַרְצַנִּ֛ים וְעַד־זָ֖ג לֹ֥א יֹאכֵֽל׃ (ה) כׇּל־יְמֵי֙ נֶ֣דֶר נִזְר֔וֹ תַּ֖עַר לֹא־יַעֲבֹ֣ר עַל־רֹאשׁ֑וֹ עַד־מְלֹ֨את הַיָּמִ֜ם אֲשֶׁר־יַזִּ֤יר לַיהֹוָה֙ קָדֹ֣שׁ יִהְיֶ֔ה גַּדֵּ֥ל פֶּ֖רַע שְׂעַ֥ר רֹאשֽׁוֹ׃
(1) יהוה spoke to Moses, saying: (2) Speak to the Israelites and say to them: If any men or women explicitly utter a nazirite’s vow, to set themselves apart for יהוה, (3) they shall abstain from wine and any other intoxicant; they shall not drink vinegar of wine or of any other intoxicant, neither shall they drink anything in which grapes have been steeped, nor eat grapes fresh or dried. (4) Throughout their term as nazirite, they may not eat anything that is obtained from the grapevine, even seeds or skin. (5) Throughout the term of their vow as nazirite, no razor shall touch their head; it shall remain consecrated until the completion of their term as nazirite of יהוה, the hair of their head being left to grow untrimmed.
YES, BE A NAZIRITE
(14) If a man said: "I will be a nazirite if I will perform this or that," or "if I will not perform," or something of the sort, he is a sinful person; such naziriteship is of the sinful. If, however, one vows to God in a way of holiness, he does a good thing and deserves praise. Concerning such a man it is written: "His consecration to God is upon his head … he is consecrated to the Lord" (Numbers 6:7-8). Scripture considers him the equal of a prophet, as it is written: "I raised up some of your sons as prophets, and some of your young men as nazirites" (Amos 2:11).
Ramban (Nachmanides) on Numbers 6:14
And the reason that he must bring a sin offering on the day that he completes his days of being a Nazirite? It is not explained, but the most simple explanation is that this man sins against his soul on this day of the completion of his Naziritehood; for until now he was separated in sanctity and the service of God, and he should therefore have remained separated forever, continuing all his life consecrated and sanctified to his God, as it is written (Amos 2:11): ‘And I raised up prophets from among your sons and nazirites from among your young men.’, and also later in Numbers, verse 8, ‘Throughout his term as Nazirite, he is holy to Adonai.’ Thus he requires atonement, since he goes back to be defiled by worldly desires.
NO, DON'T BE A NAZIRITE
If one should argue: since envy, passion, and pride and such are an evil path... then I shall divorce and separate myself utterly from them until I eat no meat nor drink wine, nor marry, nor reside in a comfortable dwelling nor wear fine clothes but only wool and sackcloth after the manner of the heathen priests – this is also an evil path and it is forbidden to walk therein as is stated in the case of the Nazirite, who is called a sinner, since it is said of the Nazir: 'And make atonement for him, for that he sinned by reason of the soul.’. And our Sages go on to say that if the Nazir only separated himself from wine and needed to make expiation, then one who separates from all things--all the more so. Therefore our Sages commanded that a person should only deny oneself those things denied him by the Torah, and should not--by vows or oaths--forbid himself from other, permitted things. One should not inflict on oneself vows of abstinence on things permitted to them. From this principle, we can derive that the path of total abstinence is not a good one.
Rabbi Lord Jonathan Sacks:
Maimonides is teaching us a profound truth, that the moral life is not always simple: a matter of black and white, good and evil, right and wrong. It usually is, but not always. Viewed from the perspective of personal perfection, the nazirite is good and holy. But from the perspective of Jewish faith as a whole, such a life is not an ideal. Judaism wants us to celebrate life, not retreat from it.
Nechama Leibowitz
The sin is not in becoming a Nazirite or in ceasing to be one. The sin referred to concerns that which preceded the Nazirite vow. Previous inability to control and discipline one's desires, within the bounds imposed by the Torah, had made it necessary for the person concerned to restrict themselves even further, and vow themselves to abstinence. The Nazirite vow was thus a necessary but extreme medicine for spiritual ills.
Rabbi Dr. Lisa Grushcow
Here is what I find most beautiful. The laws surrounding the Nazirite are followed in our parashah by the priestly benediction, Birkat Kohanim (Numbers 6:22-27). This blessing is transmitted by the priests but ultimately comes from God. “A mortal does not know with what to bless another,” notes the Ketav Sofer (Hungarian, 19th century), “for what he thinks may be good for another person may in reality be bad for him, and vice versa. Rather, may God, who knows what is good for you, bless you.” Parashat Naso recognizes that as human beings — in all our individuality — we make mistakes, and we are flawed; it is not despite this, but because of it, that we are worthy of blessing. (https://reformjudaism.org/learning/torah-study/torah-commentary/nazirite-vow-connecting-higher-power)