NUM 6:5

5 All the time of his separating, or of his avow holding, a razor shall not pass upon his head, unto the day(s) be fulfilled in which he is hallowed to the Lord; he shall be holy, and the hair of his head shall wax. (All the time of his separation, or of the keeping of his vow, a razor shall not pass over his head, until the days be fulfilled in which he is consecrated, or is dedicated, to the Lord; he shall be holy, and his head hair shall grow.)