What is the ruling if a wife redeems herself for a specific fabric stipulated to be cotton, but it turns out to be linen?

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If the wife redeems herself for a fabric stipulated to be cotton, but it is found to be linen, the fabric must be returned, and the husband is not permitted to keep it. This is because linen is a different genus, and the difference between genera is treated like the difference between distinct specific items, unlike the case where a *marwiy* was exchanged for a *harwiy* (where the genus was the same).