The law of the Nazirite vow, set out in Numbers chapter 6 of the Hebrew Bible, describes a voluntary form of consecration open to anyone, not a priestly office: for a set period, or in rare cases for life, a Nazirite abstained from wine and grape products, avoided contact with the dead, and let their hair grow without cutting it, a visible outward sign of the inward vow rather than the source of any power in itself. Most Nazirite vows in the biblical text are temporary, taken up and then formally concluded with a specific ritual, including a final haircut and offering, at a designated sanctuary.
Samson, described in the Book of Judges as a Nazirite from birth rather than by his own choice, is the exception the story is best remembered for, and popular retelling routinely simplifies his account into a claim that his uncut hair itself contained his strength. The biblical text is more precise than that: it presents Samson's strength as a gift tied to his covenant relationship with God, of which the uncut hair was the visible sign and the broken vow, when Delilah has it cut, the occasion on which that relationship and the strength that came with it lapsed, a distinction between sign and source that the story's later cultural life has not always preserved.