And the LORD spoke to Moses, saying, “Speak to the people of Israel and say to them, When either a man or a woman makes a special vow, the vow of a Nazirite, to separate himself to the LORD, he shall separate himself from wine and strong drink. He shall drink no vinegar made from wine or strong drink and shall not drink any juice of grapes or eat grapes, fresh or dried. All the days of his separation he shall eat nothing that is produced by the grapevine, not even the seeds or the skins.
“All the days of his vow of separation, no razor shall touch his head. Until the time is completed for which he separates himself to the LORD, he shall be holy. He shall let the locks of hair of his head grow long.
“All the days that he separates himself to the LORD he shall not go near a dead body. Not even for his father or for his mother, for brother or sister, if they die, shall he make himself unclean, because his separation to God is on his head. All the days of his separation he is holy to the LORD.
“And if any man dies very suddenly beside him and he defiles his consecrated head, then he shall shave his head on the day of his cleansing; on the seventh day he shall shave it. On the eighth day he shall bring two turtledoves or two pigeons to the priest to the entrance of the tent of meeting, and the priest shall offer one for a sin offering and the other for a burnt offering, and make atonement for him, because he sinned by reason of the dead body. And he shall consecrate his head that same day and separate himself to the LORD for the days of his separation and bring a male lamb a year old for a guilt offering. But the previous period shall be void, because his separation was defiled.
“And this is the law for the Nazirite, when the time of his separation has been completed: he shall be brought to the entrance of the tent of meeting, and he shall bring his gift to the LORD, one male lamb a year old without blemish for a burnt offering, and one ewe lamb a year old without blemish as a sin offering, and one ram without blemish as a peace offering, and a basket of unleavened bread, loaves of fine flour mixed with oil, and unleavened wafers smeared with oil, and their grain offering and their drink offerings. And the priest shall bring them before the LORD and offer his sin offering and his burnt offering, and he shall offer the ram as a sacrifice of peace offering to the LORD, with the basket of unleavened bread. The priest shall offer also its grain offering and its drink offering. And the Nazirite shall shave his consecrated head at the entrance of the tent of meeting and shall take the hair from his consecrated head and put it on the fire that is under the sacrifice of the peace offering. And the priest shall take the shoulder of the ram, when it is boiled, and one unleavened loaf out of the basket and one unleavened wafer, and shall put them on the hands of the Nazirite, after he has shaved the hair of his consecration, and the priest shall wave them for a wave offering before the LORD. They are a holy portion for the priest, together with the breast that is waved and the thigh that is contributed. And after that the Nazirite may drink wine.
“This is the law of the Nazirite. But if he vows an offering to the LORD above his Nazirite vow, as he can afford, in exact accordance with the vow that he takes, then he shall do in addition to the law of the Nazirite.” (Numbers 6:1-21 ESV)
Continuing to deal with purity in the camp in preparation for war in Canaan, Yahweh makes sure that those who take a temporary vow of devotion to Him, called the Nazarite or the separated one’s vow, did what was required to maintain the integrity of the vow and thus the purity of the camp by following His requirements. A Nazarite grew his or her hair long and did not cut it throughout the time of the vow, to show their devotion to God and followed some strict dietary rules and kept from touching dead bodies.
But if one inadvertently touched a dead body a cleansing must take place, including shaving of the hair, and the vow restarted and completed for the same length of time the Nazarite stipulated originally. Then, when the time of the vow was over, the Nazarite was to offer sacrifice and burn his or her hair on the altar. Any additional vows made must also be kept.
Though every Israelite was to be devoted to Yahweh, the Nazarite vow was a special way to demonstrate that. Believers today are all to be devoted to Christ, but there may be special disciplines we take upon ourselves at times to demonstrate our devotion to Him (fasting, silence, chastity, etc.). Doing these things does not make us more holy and are certainly not required. They are strictly voluntary. It is going out of our way to tell God we love Him.
Sometimes we think making a vow to God will obligate God to us and so we are tempted to think we can manipulate Him this way or strengthen ourselves in our resolve to live for Him. These are both mistaken ideas about the vow. Making a vow to God does not obligate Him to us but us to Him. And taking a vow to be more holy is not a helpful way of becoming more holy. We can’t just screw up our intensity and will power to become more holy. Purity in the camp for us comes from spending quality time with Christ in prayer and communion with Him in His Word.