Is a partner allowed to use partnership assets as collateral (rahn) for a joint debt, or take collateral for a joint receivable?

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There are two views on whether a partner can mortgage assets for a debt owed by both, or take collateral for a receivable owed to both. The sounder opinion is that it is permissible when necessary, as collateralization is for fulfillment (evasion) and taking collateral is for demanding fulfillment (istifa'). Since the partner has the right to fulfill and demand fulfillment, they possess the means to achieve the ends for which collateral is sought. The second view prohibits it due to the inherent risk. There is no distinction whether the transaction was initiated by the partner who managed the contract or another party, because custody (qabd) is a right of the contract, and contractual rights are not exclusive to the acting party; thus, what is intended for those rights is also not exclusive.