Numbers 6:5

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.

All the days of the vow of his separation,.... Be the time he has vowed to be a Nazarite a week, a, month, or more, even a thousand days, but not less than thirty, as Ben Gersom observes:

there shall no razor come upon his head; he might not shave his beard, nor cut off his locks, and shave his head, nor cut short his locks with a pair of scissors, nor any with anything by which the hair may be removed, as Ben Gersom; nor pluck off his hair with his hands, as Maimonides says {x}; but let it grow as long as it would during the time of his separation, which is expressed in the latter part of the verse:

until the days be fulfilled, in the which he separateth himself unto the LORD; to his service, to which he wholly addicted himself as long as his vow continued:

he shall be holy; separate from other men, and their practices and customs, and spend his time in holy exercises, in a religious way, and abstain from what might be a temptation to sin, or in the least hinder him in his acts of devotion:

and shall let the locks of his hair grow; two reasons Fagius gives of this part of the law, the one is, because of the mystery of it; letting the hair grow signified an increase of virtue or grace, as Samson's strength was increased and became very great while his hair was not cut; and so spiritual Nazarites, while they are in the way of their duty, grow in grace, and in knowledge of God and Christ, and all divine things, and grow stronger and stronger in the Lord, and in the power of his might; and Ainsworth hints at the same thing, and also supposes it might be an emblem of the subjection of the saints to Christ, as the letting the hair grow was a sign of the woman's subjection to man: the other is, that it was appointed to take the Israelites off of the errors and superstitious they had imbibed in Egypt, by ordering them to perform those rites and ceremonies to the honour of the true God, which they had used in the service of demons; and for this he cites a passage out of Cyrill; but it does not appear, by any good authority, that such a custom obtained among the Egyptians, or any other Gentiles so early; and what were used among them in later times took their rise from hence, and were imitations of this law; though there seems to be no great likeness between this law of Nazariteship and the customs of the Heathens, who used to consecrate their hair to their deities, Apollo, Hercules, Bacchus, Minerva, and Diana: what seems best to agree is what Lucian says {y}, who observes, that young men consecrate their beards, and let their hair grow, consecrated from their birth, which they afterwards cut and lay up in vessels in the temple, some of gold, others of silver.

{x} Hilchot Nezirut, c. 5. sect. 11.
{y} De Dea Syria.