Linked from
The 13 pages that link to Oath, each with the reason it gives.
InitiationRelated: Some initiations use sworn commitments to formalize new duties.
PerjuryRelated: Perjury requires a statement made under an oath or legally equivalent affirmation.
VowRelated: An oath resembles a vow but often emphasizes testimony or formal duty.
Notary publicRelated: Administering oaths and affirmations is a core notarial power.