Halakhah к Бамидбар 6:5

That the nazirite not shave his hair: That the nazirite not shave his hair, all of the days of his naziriteness, as it is stated (Numbers 6:5) "a razor shall not pass over his head."

The commandment of growing the hair of the nazirite: That the nazirite - who is the person who separated himself from wine - is commanded to let his head hair grow for all the days of his naziriteness for God, as it states (Numbers 6:5), "he shall grow the locks of his head." And the language of Mekhilta (Sifra Zuta on Numbers 6:5) is "'He shall grow the hair' is a positive commandment. From where [do I know there is also a] negative commandment? Hence, it teaches to say 'a blade shall not pass over his head.'"