Is the pledging (mortgaging) of a sold item valid if done during the option period?

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The pledging of a sold item during the period of the option to revoke the sale is invalid. However, if the buyer pledges the item, and the option belongs solely to the buyer, the transaction is valid, but the buyer's right of option is voided. This position is held by Abu Bakr and is the school of thought (Madhab) of Al-Shafi'i. The same ruling applies to the buyer's sale or other dispositions of the item during the option period.