Upon what basis must an oath be taken concerning the actions of another person?

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When an oath concerns the actions of another person, it must be based on a negation of knowledge (Nafy Al-'Ilm), especially if the claim is related to debt, usurpation, or a physical transgression, as this is an oath about what one cannot fully encompass. If the claim is affirmative, such as alleging that another person confessed or sold something, and there is supporting evidence, the oath is taken upon certainty (Al-Batt wal-Qat'). If an oath is taken based on certainty when negation of knowledge is sufficient, the oath is valid, and the implied understanding is that the person is swearing based on their knowledge, similar to a witness testifying about the number of heirs.