Numbers 6:9

Day. That none might escape; (Theodoret, q. 11) though the Hebrew may imply that the hair was only shaved on the ninth day, when he was to be purified, chap. xix. 12. Then the Nazarite had to begin again, as if he had done nothing, (Calmet) if his vow were only for a time. Those who had taken a vow for life never shaved.