She swore a false oath; how can she expiate that?

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Check below answers in case you are looking for other related questions:
Ruling on placing one’s hand on the Bible when swearing
Which takes precedence: making up missed Ramadan fasts or fasting in expiation for breaking an oath or fulfilment of a vow?

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Related Answers:
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Ruling on placing one’s hand on the Bible when swearing
Which takes precedence: making up missed Ramadan fasts or fasting in expiation for breaking an oath or fulfilment of a vow?

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