Numbers 6

And the LORD said to Moses, “Speak to the Israelites and tell them that if a man or woman makes a special vow, the vow of a Nazirite to separate himself to the LORD, he is to abstain from wine and strong drink. He must not drink vinegar made from wine or strong drink, and he must not drink any grape juice or eat fresh grapes or raisins. All the days of his separation, he is not to eat anything that comes from the grapevine, not even the seeds or skins.

For the entire period of his vow of separation, no razor shall touch his head. He must be holy until the time of his separation to the LORD is complete; he must let the hair of his head grow long.

Throughout the days of his separation to the LORD, he must not go near a dead body. Even if his father or mother or brother or sister should die, he is not to defile himself, because the symbol of consecration to his God is upon his head. Throughout the time of his separation, he is holy to the LORD.