Numbers 6:1-7

Again the LORD spoke to Moses, saying, “Say to the sons of Israel, ‘When a man or a woman makes a special vow, the vow of a Nazirite, that is, one separated and dedicated to the LORD, he shall abstain from wine and strong drink; he shall drink no vinegar, whether made from wine or strong drink, nor shall he drink any grape juice nor eat fresh or dried grapes. [Luke 1:15] All the time of his separation he shall not eat anything produced from the grapevine, from the seeds even to the skins. ‘All the time of the vow of his separation no razor shall be used on his head. Until the time of his separation to the LORD is completed, he shall be holy, and shall let the hair of his head grow long. ‘All the time that he separates himself to the LORD he shall not go near a dead body. He shall not make himself [ceremonially] unclean for his father, mother, brother, or sister, when they die, because [the responsibility for] his separation to God is on his head.