Halacha

הלכה א
הַנְּזִירוּת הוּא נֵדֶר מִכְּלַל נִדְרֵי אִסָּר שֶׁנֶּאֱמַר (במדבר ו ב) "כִּי יִדֹּר נֶדֶר נָזִיר" וְגוֹ'. וּמִצְוַת עֲשֵׂה שֶׁיְּגַדֵּל שְׂעַר רֹאשׁוֹ שֶׁנֶּאֱמַר (במדבר ו ה) "גַּדֵּל פֶּרַע שְׂעַר רֹאשׁוֹ". וְאִם גִּלֵּחַ בִּימֵי נִזְרוֹ עוֹבֵר בְּלֹא תַּעֲשֶׂה שֶׁנֶּאֱמַר (במדבר ו ה) "תַּעַר לֹא יַעֲבֹר עַל רֹאשׁוֹ". וְכֵן אָסוּר לְהִטָּמֵא לַמֵּתִים אוֹ לֶאֱכל דְּבָרִים שֶׁאֲסָרָן הַכָּתוּב עָלָיו (במדבר ו ד) "מִגֶּפֶן הַיַּיִן" (במדבר ו ד) (במדבר ו ח) "כָּל יְמֵי נִזְרוֹ":
כסף משנה
1.
A nazirite vow is one of the types of vows involving prohibitions,1Thus it is governed by the laws mentioned in the previous set of halachot. As mentioned in the beginning of Hilchot Nedarim, there are two types of vows: vows involving prohibitions and vows taking on an obligation to bring sacrifices. A nazirite vow also involves bringing sacrifices, as will be explained. Nevertheless, it is considered primarily a vow involving prohibitions (Radbaz).as [Numbers 6:2] states: "When one will take a nazirite vow...." It is a positive commandment for [a nazirite] to let the hair of his head grow,2Sefer HaMitzvot (positive commandment 92) and Sefer HaChinuch (mitzvah 374) include this commandment among the 613 mitzvot of the Torah. as [ibid.:5] states: "He shall let the mane of the hair of his head grow." If he cuts [his hair] in the midst of the days of his nazirite vow, he violates a negative commandment,3Sefer HaMitzvot (negative commandment 209) and Sefer HaChinuch (mitzvah 373) include this commandment among the 613 mitzvot of the Torah. as [ibid.] states: "A razor shall not pass over his head." Similarly, he is forbidden to contract ritual impurity from a corpse4Sefer HaMitzvot (negative commandments 207-208) and Sefer HaChinuch (mitzvot 375-376) include two prohibitions involving this matter among the 613 mitzvot of the Torah. See Chapter 5 which describes this prohibition. or eat those products of a grape vine which the Torah forbids him from eating5This includes prohibitions against drinking wine and eating fresh grapes, raisins, grape seeds, and grape peels. Sefer HaMitzvot (negative commandment 202-206) and Sefer HaChinuch (mitzvot 368-372) include five prohibitions against partaking of these grape products among the 613 mitzvot of the Torah. throughout the entire span of his nazirite vow.6The Radbaz explains that the Rambam does not mention these prohibitions in the order that they are mentioned in the Torah, not in the order that they are mentioned in the Mishnah. The rationale is that the mitzvah of letting one's hair grow is mentioned first because it involves both a positive and a negative commandment.

הלכה ב
עָבַר וְגִלֵּחַ אוֹ נִטְמָא אוֹ אָכַל מִגֶּפֶן הַיַּיִן הֲרֵי זֶה לוֹקֶה שְׁתַּיִם. אַחַת מִשּׁוּם (במדבר ל ג) "לֹא יַחֵל דְּבָרוֹ" שֶׁכּוֹלֵל כָּל הַנְּדָרִים. וְאַחַת מִשּׁוּם דָּבָר שֶׁעָבַר עָלָיו מִדְּבָרִים שֶׁאֲסוּרִין אִסּוּר מְיֻחָד עַל הַנָּזִיר:
כסף משנה
2.
When [a nazirite] transgressed and cut his hair, became impure [due to contact with a corpse], or partook of wine grapes, he receives two sets of lashes:7For with his deed, he has violated two of the Torah's prohibitions.one because of the prohibition "He shall not desecrate his word,"8Which applies with regard to the violation of all vows, as stated in Hilchot Nedarim 1:5. and one because of the prohibition that he transgressed from the unique prohibitions that apply to a nazirite.9If he violates his nazirite vow in several ways, e.g., he eats grapes and becomes impure, he receives lashes according to the number of violations involved (Radbaz).

הלכה ג
נָדַר בְּנָזִיר וְקִיֵּם נִדְרוֹ כְּמִצְוָתוֹ הֲרֵי זֶה עוֹשֶׂה שָׁלֹשׁ מִצְוֹת עֲשֵׂה. הָאַחַת (במדבר ל ג) "כְּכָל הַיֹּצֵא מִפִּיו יַעֲשֶׂה" וַהֲרֵי עָשָׂה. וְהַשְּׁנִיָּה (במדבר ו ה) "גַּדֵּל פֶּרַע שְׂעַר רֹאשׁוֹ" וַהֲרֵי גִּדֵּל. וְהַשְּׁלִישִׁית תִּגְלַחְתּוֹ עִם הֲבָאַת קָרְבְּנוֹתָיו שֶׁנֶּאֱמַר (במדבר ו יח) "וְגִלַּח הַנָּזִיר פֶּתַח אֹהֶל מוֹעֵד" וְגוֹ':
כסף משנה
3.
When a person takes a nazirite vow and fulfills his vow according to the mitzvah, he has performed three positive commandments: a) "He shall act in accordance with all that he uttered with his mouth,"10I.e., the commandment to observe the vows one takes. See Hilchot Nedarim 1:4. and he has acted [accordingly], b) "He shall let the mane of the hair of his head grow," and he has let it grow, and c) shaving and bringing his sacrifices,11Which is done at the fulfillment of one's nazirite vow. Sefer HaMitzvot (positive commandment 93) and Sefer HaChinuch (mitzvah 377) include this commandment among the 613 mitzvot of the Torah. See Chapter 8 which describes this procedure. as [ibid.:18] states: "And the nazirite shall shave at the entrance to the Tent of Meeting."

הלכה ד
הָאוֹמֵר לֹא אֶפָּטֵר מִן הָעוֹלָם עַד שֶׁאֶהֱיֶה נָזִיר הֲרֵי זֶה נָזִיר מִיָּד שֶׁמָּא יָמוּת עַתָּה. וְאִם אֵחֵר נְזִירוּתוֹ הֲרֵי זֶה עוֹבֵר בְּבַל (דברים כג כב) "תְּאַחֵר לְשַׁלְּמוֹ" וְאֵין לוֹקִין עַל לָאו זֶה:
כסף משנה
4.
When a person says: "I will not depart from the world until I become a nazirite," he becomes a nazirite immediately, lest he die at that time. If he delays [implementing] his nazirite vow, he transgresses the prohibition:12Deuteronomy 23:22. As the Rambam states in Hilchot Arachin VaCharamim 1:1, this prohibition applies to any person who delays keeping the vows and pledges he makes. He does not, however, list this prohibition as one of the 613 mitzvot in these halachot, but instead, in Hilchot Ma'aseh HaKorbanot (in the introduction to those halachot and in Chapter 14, Halachah 13).
See also Hilchot Arachin 6:33 which uses this law as support for the principle that a pledge to perform a mitzvah is considered as a vow.
"Do not delay in paying it." Lashes are not given for the violation of this prohibition.13For as stated in Hilchot Sanhedrin 18:2, lashes are not given for the violation of a prohibition that does not involve a deed. Note, however, Chapter 5, Halachah 21.

הלכה ה
אֵין אוֹמְרִין בִּנְזִירוּת עַד שֶׁיּוֹצִיא בִּשְׂפָתָיו דָּבָר שֶׁמַּשְׁמָעוֹ אֵצֶל כָּל הָעָם כָּעִנְיָן שֶׁבְּלִבּוֹ. אֶלָּא כֵּיוָן שֶׁגָּמַר בְּלִבּוֹ וְהוֹצִיא בִּשְׂפָתָיו דְּבָרִים שֶׁעִנְיָנָם שֶׁיִּהְיֶה נָזִיר אַף עַל פִּי שֶׁהֵן עִנְיָנוֹת רְחוֹקוֹת וְאַף עַל פִּי שֶׁאֵין בְּמַשְׁמָעָן לְשׁוֹן נְזִירוּת הֲרֵי הוּא נָזִיר:
כסף משנה
5.
With regard to a nazirite vow, we do not say: [The vow does not take effect] until he makes a statement that every person would be able to understand [that] in his heart [he desired to take a nazirite vow]. Instead, since he made a decision in his heart to take a nazirite vow and verbally expressed concepts that suggest this intent, he is a nazirite although these concepts are distant and [their simple meaning] does not communicate the concept of a nazirite vow.14This concept, which the Rambam illustrates in the following halachot, expresses the principle (see Nedarim 5b) that yadot nedarim, literally "handles of vows," are considered equivalent to vows themselves.

הלכה ו
כֵּיצַד. הֲרֵי שֶׁהָיָה נָזִיר עוֹבֵר לְפָנָיו וְאָמַר אֶהְיֶה הֲרֵי זֶה נָזִיר הוֹאִיל וּבְלִבּוֹ הָיָה שֶׁיִּהְיֶה כְּמוֹ זֶה וְאַף עַל פִּי שֶׁלֹּא פֵּרֵשׁ וְאָמַר אֶהְיֶה כְּמוֹ זֶה. וְכֵן אִם אָחַז בִּשְׂעָרוֹ וְאָמַר אֶהְיֶה נָאֶה אוֹ אֱהֵא מְכַלְכֵּל אוֹ אֲהָא מְסַלְסֵל אוֹ שֶׁאָמַר הֲרֵינִי מְסַלְסֵל אוֹ הֲרֵינִי מְכַלְכֵּל אוֹ הֲרֵי עָלַי לְשַׁלֵּחַ פֶּרַע הֲרֵי זֶה נָזִיר וְהוּא שֶׁיִּגְמֹר בְּלִבּוֹ לְהַזִּיר:
כסף משנה
6.
What is implied? A nazirite was passing in front of a person and he said: "I will be," he is a nazirite. Since in his heart, he intended to say that he will be like that person, [it is considered as if he made such a statement] even though he did not explicitly say: "I will be like him." Similarly, if he took hold of his hair15According to the Rambam, when he makes such statements while holding his hair, it is not necessary that a nazirite pass in front of him for his statement to be binding. and said: "I will become attractive," "I will grow my hair," "I will cultivate my hair,"16The Hebrew uses two expressions to communicate this and the previous concept. Our translations for these terms are taken from Rav Kappach's translation of the Rambam's Commentary to the Mishnah (Nazir 1:1). "I will let my hair grow long," he is a nazirite, provided he made such a decision in his heart.

הלכה ז
אָמַר הֲרֵי עָלַי צִפֳּרִים אַף עַל פִּי שֶׁהָיָה נָזִיר עוֹבֵר לְפָנָיו וְאַף עַל פִּי שֶׁהָיָה בְּלִבּוֹ לְהַזִּיר אֵינוֹ נָזִיר וַהֲרֵי זֶה כְּמִי שֶׁלֹּא הוֹצִיא בִּשְׂפָתָיו כְּלוּם:
כסף משנה
7.
If he says: "I am obligated to bring doves [as offerings],17The offering a nazirite would bring if he became impure (see Numbers 6:10 . he is not a nazirite even if a nazirite is passing in front of him and even if he had the intent of becoming a nazirite. It is as if he did not say anything.18I.e., with regard to a nazirite vow. Since it is possible that his statement meant that he intended to offer the doves as a sacrifice, it is not considered as implying a nazirite vow. From the Rambam's Commentary to the Mishnah (loc. cit.), it appears that the person is liable to bring these doves as a voluntary offering. It is questionable if here the Rambam is negating that implication.

הלכה ח
כָּל כִּנּוּיֵי נְזִירוּת כִּנְזִירוּת. כֵּיצַד. מְקוֹמוֹת הָעִלְּגִים שֶׁמְּשַׁנִּין אֶת הַדִּבּוּר וְאָמַר שָׁם הֲרֵינִי נָזִיק נָזִיחַ פָּזִיחַ הֲרֵי זֶה נָזִיר:
כסף משנה
8.
All nicknames for a nazirite vow are considered like a nazirite vow.
What is implied? In places where people mispronounce the words they use, if one says: "I am a nazik, a naziach, a paziach,19In his Commentary to the Mishnah (loc. cit.), the Rambam writes that gentiles who lived among the Jewish people would mispronounce the word nazir in this manner. As such, there would be some Jews who would make similar mistakes. See parallel concepts in Hilchot Sh'vuot 2:5, Hilchot Nedarim 1:16. he is a nazirite."

הלכה ט
הָאוֹמֵר הֲרֵינִי נָזִיר מִן הַחַרְצַנִּים בִּלְבַד אוֹ מִן הַזַּגִּים בִּלְבַד אוֹ הֲרֵינִי נָזִיר מִן הַתִּגְלַחַת אוֹ הֲרֵינִי נָזִיר מִן הַטֻּמְאָה בִּלְבַד הֲרֵי זֶה נָזִיר גָּמוּר וְכָל דִּקְדּוּקֵי נְזִירוּת עָלָיו וְאַף עַל פִּי שֶׁלֹּא הָיָה בְּלִבּוֹ לְהַזִּיר אֶלָּא מִדָּבָר זֶה בִּלְבַד הוֹאִיל וְדָבָר שֶׁנָּזַר מִמֶּנּוּ אָסוּר עַל הַנְּזִירִים הֲרֵי זֶה נָזִיר גָּמוּר:
כסף משנה
9.
If a person says: "I am a nazirite only with regard to grape seeds" or "...with regard to grape peels," "I am a nazirite with regard to shaving," or "I am a nazirite only with regard to impurity," he is a nazir in the complete sense and he must keep all the particular laws incumbent on nazirites even though his intent was to forbid himself only with regard to the particular he mentioned. Since the matter concerning which he took the nazirite vow is forbidden to nazirites, he is a nazirite in the full sense of the term.20I.e., since he used the term "nazirite" and the object which he mentioned is forbidden to nazirites, the nazirite restrictions all take effect. Note the contrast to the following halachah.

הלכה י
אֲבָל הָאוֹמֵר הֲרֵינִי נָזִיר מִן הַגְּרוֹגָרוֹת אוֹ מִן הַדְּבֵלָה וְכַיּוֹצֵא בָּהֶן הֲרֵי זֶה אָסוּר בָּהֶן וְאֵינוֹ נָזִיר:
כסף משנה
10.
If, however, one says: "I am a nazirite from dried figs," "...from cakes of dried figs," or the like, he is forbidden [to partake of] the article specified, but he is not a nazirite.21Because the term nazirite does not apply with regard to those objects.

הלכה יא
מָזְגוּ לוֹ כּוֹס שֶׁל יַיִן וְנָתְנוּ לוֹ לִשְׁתּוֹת וְאָמַר הֲרֵינִי נָזִיר מִמֶּנּוּ הֲרֵי זֶה נָזִיר גָּמוּר. וְאִם הָיָה מַר נֶפֶשׁ אוֹ כּוֹעֵס אוֹ מִתְאַבֵּל וְהָיוּ מְבַקְּשִׁין מִמֶּנּוּ שֶׁיִּשְׁתֶּה כְּדֵי לְשַׁכֵּחַ עֲמָלוֹ וְאָמַר הֲרֵי זֶה נָזִיר מִמֶּנּוּ הֲרֵי זֶה אָסוּר בְּאוֹתוֹ הַכּוֹס בִּלְבַד וְאֵינוֹ נָזִיר. שֶׁלֹּא נִתְכַּוֵּן זֶה אֶלָּא שֶׁלֹּא יִשְׁתֶּה כּוֹס זֶה:
כסף משנה
11.
When a cup of wine was mixed22I.e., in the Talmudic era, the wine was very strong. Hence it was customary to mix water into wine before serving it. for a person and given to him to drink and he said: "I am a nazirite from it," he is a nazirite in the complete sense.23I.e., the situation is comparable to those described in Halachah 9. If he was a morose person, angry, or in mourning and the others were trying to have him drink to release his burden and he said: "I am a nazirite from this [cup]," he is forbidden to drink only that cup, but he is not a nazirite. [The rationale is that] his intent was only that he would not drink that cup.

הלכה יב
וְכֵן שִׁכּוֹר שֶׁנָּתְנוּ לוֹ כּוֹס כְּדֵי לְרַוּוֹתוֹ וְאָמַר הֲרֵי זֶה נָזִיר מִמֶּנּוּ הֲרֵי זֶה אָסוּר בְּאוֹתוֹ הַכּוֹס בִּלְבַד וְאֵינוֹ חַיָּב בִּנְזִירוּת שֶׁלֹּא נִתְכַּוֵּן זֶה אֶלָּא שֶׁלֹּא יְשַׁכְּרוּ אוֹתוֹ יוֹתֵר מִדַּאי. וְאִם הִגִּיעַ לְשִׁכְרוּתוֹ שֶׁל לוֹט אֵין דְּבָרָיו כְּלוּם וְאֵינוֹ חַיָּב עַל כָּל עֲבֵרָה שֶׁיַּעֲשֶׂה שֶׁמִּשֶּׁהִגִּיעַ לְשִׁכְרוּתוֹ שֶׁל לוֹט אֵינוֹ בֶּן חִיּוּב:
כסף משנה
12.
Similarly, if a drunken man was given a cup to make him totally inebriated and he said: "I am a nazirite from it," he is forbidden to drink only that cup, but he is not a nazirite. [The rationale is that his intent was] only that they should not have him become overly drunk. If he was as drunk as Lot24Who became so drunk that he lost all consciousness of his actions. See Genesis, ch. 19. his statements are of no consequence and he is not liable for any transgression that he performs. For when he reaches a state of inebriation equivalent to Lot's, he is not liable at all.25I.e., he is considered like a mentally and emotionally incapable person (a shoteh). See Hilchot Ishut 4:18, Hilchot Mechirah 29:18.

הלכה יג
הָאוֹמֵר הֲרֵינִי נָזִיר עַל מְנָת שֶׁאֶהֱיֶה שׁוֹתֶה יַיִן אוֹ מִטַּמֵּא לַמֵּתִים אוֹ מְגַלֵּחַ שְׂעָרִי הֲרֵי זֶה נָזִיר וְאָסוּר בְּכֻלָּם. מִפְּנֵי שֶׁהִתְנָה עַל מַה שֶּׁכָּתוּב בַּתּוֹרָה וְכָל הַמַּתְנֶה עַל הַכָּתוּב בַּתּוֹרָה תְּנָאוֹ בָּטֵל:
כסף משנה
13.
When a person says: "I am a nazirite on the condition that I can drink wine," "...become impure because of contact with the dead," or "...cut my hair,"26I.e., he seeks to avoid keeping one or more of the obligations of the nazirite vow although he will keep the others. he is a nazirite and is forbidden to perform all of the above. [The rationale is that] he made a stipulation against what is written in the Torah and whenever one makes a stipulation against what is written in the Torah, the stipulation is nullified.27This is a general principle applying in many aspects of Torah law, e.g., Hilchot Ishut 16:9.

הלכה יד
נָדַר בְּנָזִיר וְאָמַר לֹא הָיִיתִי יוֹדֵעַ שֶׁהַנָּזִיר אָסוּר בְּיַיִן אוֹ בְּטֻמְאָה אוֹ בְּתִגְלַחַת וְאִלּוּ הָיִיתִי יוֹדֵעַ כֵּן לֹא הָיִיתִי נוֹדֵר הֲרֵי זֶה נָזִיר וְחַיָּב בְּכֻלָּם. שֶׁהֲרֵי הוּא הָיָה יוֹדֵעַ שֶׁאָסַר עַצְמוֹ בְּאֶחָד מִשְּׁלֹשָׁה מִינִין וּכְבָר בֵּאַרְנוּ שֶׁאֲפִלּוּ לֹא נָדַר אֶלָּא מֵאֶחָד מֵהֶם אָסוּר בְּכֻלָּן:
כסף משנה
14.
When a person takes a nazirite vow and [afterwards] says: "I did not know that a nazirite was forbidden to partake of wine..., "...to become impure," or "...to cut hair. Had I known this, I would not have take the vow," he is a nazirite and is obligated in all these prohibitions. [The rationale is that] he knows that he is obligated in at least one of these [prohibitions] and as we explained,28In the previous halachah. even if one took a [nazirite] vow, forbidding only one of these acts, he is forbidden in all of them.29The Ra'avad states that if a person would approach a sage and ask him to absolve his nazirite vow on these grounds, the sage would certainly consent. We are speaking about an instance when the person seeks to have the vow nullified without consulting a sage because it was taken in error. The Radbaz states that the Rambam would also accept this ruling. The Kessef Mishneh, however, does not accept this explanation.

הלכה טו
אָמַר יוֹדֵעַ הָיִיתִי שֶׁהַנָּזִיר אָסוּר בְּכָל אֵלּוּ אֲבָל הָיָה בְּדַּעְתִּי שֶׁמֻּתָּר לִי לִשְׁתּוֹת אֲנִי הַיַּיִן מִפְּנֵי שֶׁאֵינִי יָכוֹל לִחְיוֹת בְּלֹא יַיִן אוֹ מִפְּנֵי שֶׁאֲנִי קוֹבֵר אֶת הַמֵּתִים הֲרֵי זֶה אֵינוֹ נָזִיר. מִפְּנֵי שֶׁאֵלּוּ בִּכְלַל נִדְרֵי שְׁגָגוֹת שֶׁאֵינָם צְרִיכִין שְׁאֵלָה לְחָכָם כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
15.
If the person says: "I know that a nazirite is forbidden in all of the above, but I thought that it would be permitted for me to drink wine, because I cannot live without wine," or "[I thought that I would be permitted to become impure,] because I bury the dead," he is not a nazirite,30He need not observe any of the nazirite prohibitions, even the ones he had intended to observe. because his vow is included in the category of vows made in error31The Ra'avad considers this as a vow which a person is prevented from keeping by forces beyond his control, citing Nazir 11b which appears to support this interpretation. The Kessef Mishneh and the Radbaz state that while the actual wording of the Talmud fits the Ra'avad's interpretation, the Rambam's explanation can be justified. [Significantly, in his Commentary to the Mishnah (Nazir 2:4), the Rambam uses the wording suggested by the Ra'avad.] which need not be absolved by a sage, as we explained.32Hilchot Sh'vuot 3:6; Hilchot Nedarim 4:1.

הלכה טז
הָאוֹמֵר הֲרֵי יָדִי נְזִירָה הֲרֵי רַגְלִי נְזִירָה לֹא אָמַר כְּלוּם. הֲרֵי רֹאשִׁי נָזִיר כְּבֵדִי נְזִירָה הֲרֵי זֶה נָזִיר. זֶה הַכְּלָל כָּל אֵיבָר שֶׁאִם יִנָּטֵל מִן הַחַי יָמוּת אִם אָמַר הֲרֵי הוּא נָזִיר הֲרֵי זֶה נָזִיר:
כסף משנה
16.
When a person says: "My hand is a nazirite" or "My foot is a nazirite," his words are of no consequence. If, however, he says: "My head is a nazirite" or "My liver is a nazirite," he is a nazarite." This is the general principle: Whenever a person designates as a nazirite an organ upon whose removal33The Or Sameach notes that the Rambam changes slightly the wording of his source, Nazir 21b, based on his ruling in Hilchot Shechitah 8:16. There the Rambam writes that if an animal is born without a liver it may live, but if it was born with a liver and then the liver was removed, it is treifah. from a living person would cause him to die, he is a nazirite.34For it is considered as if he took the vow upon his entire person. Compare to Hilchot Arachin 2:1; Hilchot Ma'aseh HaKorbanot 15:2; Hilchot Mechirah 27:8.

הלכה יז
הָאוֹמֵר הֲרֵינִי נָזִיר כְּשֶׁיִּהְיֶה לִי בֵּן. אִם נוֹלַד לוֹ בֵּן זָכָר הֲרֵי זֶה נָזִיר. אֲבָל אִם נוֹלְדָה לוֹ בַּת אוֹ טֻמְטוּם אוֹ אַנְדְּרוֹגִינוּס אֵין זֶה נָזִיר. אָמַר הֲרֵינִי נָזִיר כְּשֶׁיִּהְיֶה לִי וָלָד אֲפִלּוּ נוֹלַד לוֹ בַּת אוֹ טֻמְטוּם וְאַנְדְּרוֹגִינוּס הֲרֵי זֶה נָזִיר. הִפִּילָה אִשְׁתּוֹ אֵינוֹ נָזִיר. חָזְרָה וְנִתְעַבְּרָה וְיָלְדָה הֲרֵי זֶה נָזִיר:
כסף משנה
17.
When a person says: "I will be a nazirite when a ben is born to me," if a son is born to him, he is a nazirite. If, however, a daughter, a tumtum,35A person whose genital area is covered by a piece of flesh and it is impossible to detect his gender. or an androgynus36A person with both male and female sexual organs (Hilchot Ishut 2:24-25). is born to him, he is not a nazirite.37Although the term ben can be translated as "offspring," its specific meaning is "son." Hence the Rambam rules in this manner.
If he says: "I will be a nazirite when offspring is born to me," even if a daughter, a tumtum, or an androgynus is born to him, he is a nazirite. If his wife miscarries, he is not a nazirite. If she becomes pregnant again and gives birth, he is a nazirite.38The fact that his wife miscarried in the interim does not negate the vow.

הפלאה הלכות נזירות פרק א
Haflaah Neziros Chapter 1