Talmud for Nazir 6:3
סְתָם נְזִירוּת שְׁלשִׁים יוֹם. גִּלַּח אוֹ שֶׁגִּלְּחוּהוּ לִסְטִים, סוֹתֵר שְׁלשִׁים יוֹם. נָזִיר שֶׁגִּלַּח בֵּין בְּזוּג בֵּין בְּתַעַר אוֹ שֶׁסִּפְסֵף כָּל שֶׁהוּא, חַיָּב. נָזִיר חוֹפֵף וּמְפַסְפֵּס, אֲבָל לֹא סוֹרֵק. רַבִּי יִשְׁמָעֵאל אוֹמֵר, לֹא יָחוֹף בַּאֲדָמָה, מִפְּנֵי שֶׁמַּשֶּׁרֶת אֶת הַשֵּׂעָר:
"Naziritism," unqualified, is for thirty days. [Even though this was taught above (1:3), it is taught again here for what follows, viz. "If he shaved, etc."] If he shaved or bandits shaved him, he offsets thirty days. [That is, he offsets it until he has a hair-growth of thirty days, when he shaves the shaving of mitzvah.] A Nazirite who shaved, whether with a pair (of scissors), or with a blade, or who plucked out anything [i.e., who uprooted even one hair] is liable (to stripes), it being written (Numbers 6:5): "A blade shall not pass" — to include all (instruments) that pass.] A Nazirite may rub [his hair with his hand] and he may part it [with his fingernails or with an instrument, so long as he does not intend to remove (any hair), for "what is not intended is permitted."], but he may not comb it [with a comb, it being certain (that some hair will be torn out), which is forbidden. Even though one who pulls out even one hair receives stripes, still, he does not offset thirty days until he shaves most of his hair with a blade or with scissors at the source of the hair.] R. Yishmael says: He may not rub (his hair) with earth [one of the depilatories], for this, [too, is certain] to cause some hair to fall out. [The halachah is in accordance with R. Yishmael.]