In the Roman Catholic Code of Canon Law, the vow and the oath are not considered acts of worship (cultus) like the liturgical celebration.
[3] The god is usually expected to grant, on entering into contracts or covenants with man, the claims his vow establishes on their benevolence, and valuing of his gratitude.
Conversely, in taking a vow, the petitioner's piety and spiritual attitude have begun to outweigh those merely ritual details of the ceremony that are all-important in magical rites.
For example, in the Maghreb (in North Africa), in time of drought the maidens of Mazouna carry every evening in procession through the streets a doll called ghonja, really a dressed-up wooden spoon, symbolizing a pre-Islamic rain-spirit.
For offering and austerity, sacrifice and suffering, are equally calculated to appease an offended deity's wrath or win his goodwill.
But to substitute an unclean for a clean beast that had been vowed, or an imperfect victim for a flawless one, was to court with certainty the divine displeasure.
Therefore, in Acts 23:21, over forty men, enemies of Paul, bound themselves, under a curse, neither to eat nor to drink till they had slain him.
Wherever individuals were concerned to create or confirm a tie connecting them with a god, a shrine or a particular religious circle, a hair-offering was in some form or other imperative.
So Achilles consecrated his hair to the river Spercheus and vowed not to cut it until he should return safe from Troy; and the Hebrew Nazarite, whose strength resided in his flowing locks, only cut them off and burned them on the altar when the days of his vow were ended, and he could return to ordinary life, having achieved his mission.
Among the ancient Chatti, as Tacitus relates (Germania, 31), young men allowed their hair and beards to grow, and vowed to court danger in that guise until they each had slain an enemy.