We have
Acts 18:18
And Paul after this tarried there yet a good while, and then took his leave of the brethren, and sailed thence into Syria, and with him Priscilla and Aquila; having shorn his head in Cenchrea: for he had a vow.
Numbers 6:2-7
2
Speak unto the children of Israel, and say unto them, When either man or woman shall separate themselves to vow a vow of a Nazarite, to separate themselves unto the LORD:
3
He shall separate himself from wine and strong drink, and shall drink no vinegar of wine, or vinegar of strong drink, neither shall he drink any liquor of grapes, nor eat moist grapes, or dried.
4
All the days of his separation shall he eat nothing that is made of the vine tree, from the kernels even to the husk.
5
All the days of the vow of his separation there shall no razor come upon his head: until the days be fulfilled, in the which he separateth himself unto the LORD, he shall be holy, and shall let the locks of the hair of his head grow.
6
All the days that he separateth himself unto the LORD he shall come at no dead body.
7
He shall not make himself unclean for his father, or for his mother, for his brother, or for his sister, when they die: because the consecration of his God is upon his head.