Numbers 6:13
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: 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:
The law provides for the close of a Nazarite separation, that when the appointed days are fulfilled the person is to be brought to the entrance of the tabernacle for the ceremonies that follow. In the Jerusalem episode involving Paul, four Christian Nazarites were nearing the end of their vows but their required purification offerings had still to be made. Those purification sacrifices were costly. Paul therefore paid the expenses for the four men and joined them in the seven days of purification.