What evidence is required to establish freedom (manumission/release from servitude) through a judicial decree?

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There are two narrations attributed to Ahmad concerning this. The first opinion holds that emancipation is established through one witness and an oath, which is preferred by Abu Bakr. This is because emancipation involves the removal of ownership, similar to a sale or a gift, and it constitutes the destruction of property, thus accepting one witness and an oath, like in sales and gifts. Additionally, while emancipation leads to the completion of legal statuses, this does not preclude its establishment by one witness and an oath, similar to how lineage is established by the testimony of women, though their testimony alone is not normally sufficient for financial matters.