What is the ruling regarding an oath to slaughter a non-related person (Ajnabi)?

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The ruling for vowing to slaughter a non-related person is the same as vowing to slaughter oneself. One narration from Ahmad mandates the slaughter of a sheep, citing the precedent of Ibn Abbas concerning a person who vowed to slaughter someone else, stating the obligation is to slaughter a ram. The rationale is that since it is a vow to slaughter a human being, the consequence is the slaughter of a ram, analogous to the vow to slaughter one's son.