If Zayd owes 'Amr food via a Salam contract, and 'Amr owes Zayd the same amount of food via another Salam contract, and Zayd tells 'Amr to take the food owed to Zayd from Zayd's debtor for 'Amr's own possession, is this valid?
Chapter on Selling Assets and Fruits
Al-Mughni
Book of Sales
Primary text
If Zayd tells 'Amr to take the food Zayd is owed from Zayd's counterparty for 'Amr's own benefit, this is invalid because 'Amr cannot take possession before Zayd himself takes possession. Regarding whether the transaction is valid for Zayd, there are two narrations. The first states it is valid because Zayd permitted the taking, resembling the agent's possession. Under this view, the food becomes Zayd's property. The second narration states it is invalid because Zayd did not appoint 'Amr as his deputy for possession, so it does not count as Zayd's possession, unlike an agent.
Supporting text
If Zayd tells 'Amr to attend so Zayd can measure it out for 'Amr to take possession, this is invalid. Whether 'Amr takes possession for himself is subject to two opinions. The preferred view is that 'Amr takes possession for himself because possession of the Salam good by its rightful recipient has occurred, making the possession valid for him, as if he intended possession for himself. If he possesses it for 'Amr, it is valid.