And this is the law of the Nazarite, when the days of his separation are fulfilled: he shall be brought unto the door of the tabernacle of the congregation: (Numbers 6:13)
These may have been of varying periods. However, the examples of Nazirites we have in the Bible are in each case lifelong: Samson (Judges 13:5), Samuel (1 Sam. 1:11), John the Baptist (Luke 1:15).