There shall no razor come upon his head— The second rule which the Nazarite was to observe was, never to shave his head during the time of his vow, but to let his hair grow, in token of austerity. For the same reasons, such persons were accustomed, not only to let their beards and hair grow, but to wear a hairy garment: such a one John the Baptist wore, as did Elijah. Besides, the not shaving was a token that the Nazarite had kept himself pure from all legal defilements; for, if he had not, he must have shaved his head: compare Numbers 6:9 with Leviticus 14:8. This rite was common to other nations; and it appears from Hosea 9:10 that the devil had his Nazarites as well as the true God: which is thought by some to be the reason why they are so often reminded in this chapter that they are separated and consecrated to the LORD. See Numbers 6:1; Numbers 6:5-8 and Archbishop Potter's Grecian Antiquities, vol. 2: p. 196, &c. The Attic laws are in general believed to have been derived from the Mosaic.
Related Commentaries of Numbers 6:5
Numbers 6:5
5 All the days of the vow of his separation there shall no razor come upon his head: until the days be fulfilled, in the which he separateth himself unto the LORD, he shall be holy, and shall let the locks of the hair of his head grow.