Numbers 6:5-7

Amplified Bible

⁵ ‘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.

⁶ ‘All the time that he separates himself to the Lord he shall not go near a dead body. ⁷ 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.