Priority between a seller's right to rescind due to a defect and a pre-emptive purchaser's (Shufi's) right of preemption when a defect is found in the exchanged slave.
General Chapter
Al-Mughni
Book of Preemption (Shuf'ah)
Primary text
When a piece of property (shaqs) is bought in exchange for a slave, and the seller of the shaqs discovers a defect in the slave, the seller has the right to return the slave and reclaim the shaqs. This right takes precedence over the right of the pre-emptive purchaser. This is because prioritizing the pre-emptive right would cause harm to the seller by invalidating the right of rescission they earned. Preemption is established to remove harm, and thus it cannot be established in a manner that causes harm, as harm is not removed by introducing harm.
Supporting text
The followers of Al-Shafi'i, in one opinion, state that the pre-emptive purchaser's right takes precedence because their right is established earlier in time, thus it must be given priority, similar to when the buyer discovers a defect in the shaqs and returns it.